diff --git a/src/plugins/cppeditor/cppautocompleter.cpp b/src/plugins/cppeditor/cppautocompleter.cpp
index 07101318628..e5560e9d969 100644
--- a/src/plugins/cppeditor/cppautocompleter.cpp
+++ b/src/plugins/cppeditor/cppautocompleter.cpp
@@ -6,7 +6,6 @@
 #include <cplusplus/MatchingText.h>
 
 #include <texteditor/tabsettings.h>
-#include <texteditor/syntaxhighlighterrunner.h>
 
 #include <QTextBlock>
 #include <QTextCursor>
@@ -17,6 +16,7 @@
 
 #include <coreplugin/editormanager/editormanager.h>
 #include <texteditor/icodestylepreferences.h>
+#include <texteditor/syntaxhighlighter.h>
 #include <texteditor/textdocument.h>
 #include <texteditor/texteditor.h>
 #include <texteditor/texteditorsettings.h>
@@ -276,9 +276,9 @@ void AutoCompleterTest::testAutoComplete()
 
     TextEditor::BaseTextEditor *cppEditor = creteCppEditor(text);
     QVERIFY(cppEditor);
-    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
     QTextCursor tc = openEditor(cppEditor);
-    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
 
     QVERIFY(!tc.isNull());
 
@@ -339,9 +339,9 @@ void AutoCompleterTest::testSurroundWithSelection()
     const QScopeGuard cleanup([] { Core::EditorManager::closeAllEditors(false); });
     TextEditor::BaseTextEditor *cppEditor = creteCppEditor(text);
     QVERIFY(cppEditor);
-    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
     QTextCursor tc = openEditor(cppEditor);
-    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
 
     QVERIFY(!tc.isNull());
 
@@ -376,9 +376,9 @@ void AutoCompleterTest::testAutoBackspace()
     const QScopeGuard cleanup([] { Core::EditorManager::closeAllEditors(false); });
     TextEditor::BaseTextEditor *cppEditor = creteCppEditor(text);
     QVERIFY(cppEditor);
-    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
     QTextCursor tc = openEditor(cppEditor);
-    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
 
     QVERIFY(!tc.isNull());
 
@@ -420,9 +420,9 @@ void AutoCompleterTest::testInsertParagraph()
     const QScopeGuard cleanup([] { Core::EditorManager::closeAllEditors(false); });
     TextEditor::BaseTextEditor *cppEditor = creteCppEditor(text);
     QVERIFY(cppEditor);
-    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
     QTextCursor tc = openEditor(cppEditor);
-    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+    QTRY_VERIFY(cppEditor->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
 
     QVERIFY(!tc.isNull());
 
diff --git a/src/plugins/cppeditor/cppcompletion_test.cpp b/src/plugins/cppeditor/cppcompletion_test.cpp
index cf8b163ab4e..fdc30e16be3 100644
--- a/src/plugins/cppeditor/cppcompletion_test.cpp
+++ b/src/plugins/cppeditor/cppcompletion_test.cpp
@@ -10,7 +10,7 @@
 
 #include <coreplugin/editormanager/editormanager.h>
 #include <texteditor/codeassist/iassistproposal.h>
-#include <texteditor/syntaxhighlighterrunner.h>
+#include <texteditor/syntaxhighlighter.h>
 #include <texteditor/textdocument.h>
 #include <texteditor/texteditor.h>
 
@@ -146,12 +146,10 @@ public:
         TextEditor::BaseTextEditor *cppEditor = qobject_cast<TextEditor::BaseTextEditor *>(m_editor);
         if (!cppEditor)
             return false;
-        if (cppEditor->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated())
+        if (cppEditor->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate())
             return true;
         return ::CppEditor::Tests::waitForSignalOrTimeout(
-            cppEditor->textDocument()->syntaxHighlighterRunner(),
-            &SyntaxHighlighterRunner::highlightingFinished,
-            5000);
+            cppEditor->textDocument()->syntaxHighlighter(), &SyntaxHighlighter::finished, 5000);
     }
 
 private:
diff --git a/src/plugins/cppeditor/cppeditordocument.cpp b/src/plugins/cppeditor/cppeditordocument.cpp
index 459ae32977a..6f2a67fede4 100644
--- a/src/plugins/cppeditor/cppeditordocument.cpp
+++ b/src/plugins/cppeditor/cppeditordocument.cpp
@@ -20,7 +20,6 @@
 #include <texteditor/storagesettings.h>
 #include <texteditor/textdocumentlayout.h>
 #include <texteditor/texteditorsettings.h>
-#include <texteditor/syntaxhighlighterrunner.h>
 
 #include <utils/infobar.h>
 #include <utils/mimeconstants.h>
@@ -164,7 +163,7 @@ QByteArray CppEditorDocument::contentsText() const
 
 void CppEditorDocument::applyFontSettings()
 {
-    if (TextEditor::SyntaxHighlighterRunner *highlighter = syntaxHighlighterRunner())
+    if (TextEditor::SyntaxHighlighter *highlighter = syntaxHighlighter())
         highlighter->clearAllExtraFormats(); // Clear all additional formats since they may have changed
     TextDocument::applyFontSettings(); // rehighlights and updates additional formats
     if (m_processor)
@@ -408,7 +407,7 @@ BaseEditorDocumentProcessor *CppEditorDocument::processor()
         connect(m_processor.data(), &BaseEditorDocumentProcessor::cppDocumentUpdated, this,
                 [this](const CPlusPlus::Document::Ptr document) {
                     // Update syntax highlighter
-                    if (SyntaxHighlighterRunner *highlighter = syntaxHighlighterRunner())
+                    if (SyntaxHighlighter *highlighter = syntaxHighlighter())
                         highlighter->setLanguageFeaturesFlags(document->languageFeatures().flags);
 
                     m_overviewModel.update(usesClangd() ? nullptr : document);
diff --git a/src/plugins/cppeditor/cpphighlighter.cpp b/src/plugins/cppeditor/cpphighlighter.cpp
index becebd11886..952d74707a2 100644
--- a/src/plugins/cppeditor/cpphighlighter.cpp
+++ b/src/plugins/cppeditor/cpphighlighter.cpp
@@ -84,8 +84,13 @@ void CppHighlighter::highlightBlock(const QString &text)
     const int firstNonSpace = tokens.first().utf16charsBegin();
 
     // Keep "semantic parentheses".
-    Parentheses parentheses = Utils::filtered(TextDocumentLayout::parentheses(currentBlock()),
-            [](const Parenthesis &p) { return p.source.isValid(); });
+    Parentheses parentheses;
+    if (TextBlockUserData *userData = TextDocumentLayout::textUserData(currentBlock())) {
+        parentheses = Utils::filtered(userData->parentheses(), [](const Parenthesis &p) {
+            return p.source.isValid();
+        });
+    }
+
     const auto insertParen = [&parentheses](const Parenthesis &p) { insertSorted(parentheses, p); };
     parentheses.reserve(5);
 
@@ -235,7 +240,8 @@ void CppHighlighter::highlightBlock(const QString &text)
     // if the block is ifdefed out, we only store the parentheses, but
 
     // do not adjust the brace depth.
-    if (TextDocumentLayout::ifdefedOut(currentBlock())) {
+    if (TextBlockUserData *userData = TextDocumentLayout::textUserData(currentBlock());
+            userData && userData->ifdefedOut()) {
         braceDepth = initialBraceDepth;
         foldingIndent = initialBraceDepth;
     }
diff --git a/src/plugins/cppeditor/cpptoolstestcase.cpp b/src/plugins/cppeditor/cpptoolstestcase.cpp
index b0151e7a813..869bbf9b84d 100644
--- a/src/plugins/cppeditor/cpptoolstestcase.cpp
+++ b/src/plugins/cppeditor/cpptoolstestcase.cpp
@@ -26,7 +26,7 @@
 #include <texteditor/codeassist/iassistproposal.h>
 #include <texteditor/codeassist/iassistproposalmodel.h>
 #include <texteditor/storagesettings.h>
-#include <texteditor/syntaxhighlighterrunner.h>
+#include <texteditor/syntaxhighlighter.h>
 #include <texteditor/texteditor.h>
 
 #include <utils/environment.h>
@@ -238,8 +238,8 @@ bool TestCase::openCppEditor(const FilePath &filePath, TextEditor::BaseTextEdito
                 [e] {
                     return e->editorWidget()
                         ->textDocument()
-                        ->syntaxHighlighterRunner()
-                        ->syntaxInfoUpdated();
+                        ->syntaxHighlighter()
+                        ->syntaxHighlighterUpToDate();
                 },
                 5000))
             return false;
diff --git a/src/plugins/cppeditor/semantichighlighter.cpp b/src/plugins/cppeditor/semantichighlighter.cpp
index d841ae19c4e..a2ae3becb79 100644
--- a/src/plugins/cppeditor/semantichighlighter.cpp
+++ b/src/plugins/cppeditor/semantichighlighter.cpp
@@ -8,7 +8,6 @@
 #include <texteditor/syntaxhighlighter.h>
 #include <texteditor/textdocument.h>
 #include <texteditor/textdocumentlayout.h>
-#include <texteditor/syntaxhighlighterrunner.h>
 
 #include <utils/algorithm.h>
 #include <utils/qtcassert.h>
@@ -67,12 +66,15 @@ void SemanticHighlighter::run()
 
 Parentheses SemanticHighlighter::getClearedParentheses(const QTextBlock &block)
 {
-    Parentheses parens = TextDocumentLayout::parentheses(block);
+    Parentheses parens;
+    if (TextBlockUserData *userData = TextDocumentLayout::textUserData(block))
+        parens = userData->parentheses();
     if (m_seenBlocks.insert(block.blockNumber()).second) {
         parens = Utils::filtered(parens, [](const Parenthesis &p) {
             return p.source != parenSource();
         });
     }
+
     return parens;
 }
 
@@ -107,7 +109,7 @@ void SemanticHighlighter::handleHighlighterResults()
     QElapsedTimer t;
     t.start();
 
-    SyntaxHighlighterRunner *highlighter = m_baseTextDocument->syntaxHighlighterRunner();
+    SyntaxHighlighter *highlighter = m_baseTextDocument->syntaxHighlighter();
     QTC_ASSERT(highlighter, return);
     incrementalApplyExtraAdditionalFormats(highlighter, m_watcher->future(), from, to, m_formatMap);
 
@@ -195,7 +197,7 @@ void SemanticHighlighter::onHighlighterFinished()
     t.start();
 
     if (!m_watcher->isCanceled() && documentRevision() == m_revision) {
-        SyntaxHighlighterRunner *highlighter = m_baseTextDocument->syntaxHighlighterRunner();
+        SyntaxHighlighter *highlighter = m_baseTextDocument->syntaxHighlighter();
         if (QTC_GUARD(highlighter)) {
             qCDebug(log) << "onHighlighterFinished() - clearing formats";
             clearExtraAdditionalFormatsUntilEnd(highlighter, m_watcher->future());
diff --git a/src/plugins/fakevim/fakevim_test.cpp b/src/plugins/fakevim/fakevim_test.cpp
index c81a40a2280..ac1f0a5797c 100644
--- a/src/plugins/fakevim/fakevim_test.cpp
+++ b/src/plugins/fakevim/fakevim_test.cpp
@@ -9,9 +9,9 @@
 #include "fakevimhandler.h"
 
 #include <coreplugin/editormanager/editormanager.h>
-#include <texteditor/texteditor.h>
+#include <texteditor/syntaxhighlighter.h>
 #include <texteditor/textdocument.h>
-#include <texteditor/syntaxhighlighterrunner.h>
+#include <texteditor/texteditor.h>
 
 #include <QtTest>
 #include <QTextEdit>
@@ -350,7 +350,7 @@ struct FakeVimTester::TestData
     void doCommand(const char *cmd) { doCommand(_(cmd)); }
     void doKeys(const QString &keys) {
         handler->handleInput(keys);
-        QTRY_VERIFY(editor()->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+        QTRY_VERIFY(editor()->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
     }
     void doKeys(const char *keys) { doKeys(_(keys)); }
 
@@ -364,7 +364,7 @@ struct FakeVimTester::TestData
         else
             i = 0;
         editor()->document()->setPlainText(_(str));
-        QTRY_VERIFY(editor()->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+        QTRY_VERIFY(editor()->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
         setPosition(i);
         QCOMPARE(position(), i);
     }
@@ -375,7 +375,7 @@ struct FakeVimTester::TestData
         QTextCursor tc = editor()->textCursor();
         tc.insertText(_(text));
         editor()->setTextCursor(tc);
-        QTRY_VERIFY(editor()->textDocument()->syntaxHighlighterRunner()->syntaxInfoUpdated());
+        QTRY_VERIFY(editor()->textDocument()->syntaxHighlighter()->syntaxHighlighterUpToDate());
     }
 
     // Simulate external position change.
diff --git a/src/plugins/glsleditor/glslhighlighter.cpp b/src/plugins/glsleditor/glslhighlighter.cpp
index eae8419a049..a6da1d6221a 100644
--- a/src/plugins/glsleditor/glslhighlighter.cpp
+++ b/src/plugins/glsleditor/glslhighlighter.cpp
@@ -190,7 +190,8 @@ void GlslHighlighter::highlightBlock(const QString &text)
 
     // if the block is ifdefed out, we only store the parentheses, but
     // do not adjust the brace depth.
-    if (TextDocumentLayout::ifdefedOut(currentBlock())) {
+    if (TextBlockUserData *userData = TextDocumentLayout::textUserData(currentBlock());
+            userData && userData->ifdefedOut()) {
         braceDepth = initialBraceDepth;
         foldingIndent = initialBraceDepth;
     }
diff --git a/src/plugins/languageclient/semantichighlightsupport.cpp b/src/plugins/languageclient/semantichighlightsupport.cpp
index b7434de18e0..431d84279df 100644
--- a/src/plugins/languageclient/semantichighlightsupport.cpp
+++ b/src/plugins/languageclient/semantichighlightsupport.cpp
@@ -10,7 +10,7 @@
 #include <texteditor/syntaxhighlighter.h>
 #include <texteditor/texteditor.h>
 #include <texteditor/texteditorsettings.h>
-#include <texteditor/syntaxhighlighterrunner.h>
+#include <texteditor/syntaxhighlighter.h>
 #include <utils/algorithm.h>
 #include <utils/mimeutils.h>
 
@@ -183,7 +183,7 @@ void SemanticTokenSupport::queueDocumentReload(TextEditor::TextDocument *doc)
 void SemanticTokenSupport::clearHighlight(TextEditor::TextDocument *doc)
 {
     if (m_tokens.contains(doc->filePath())){
-        if (TextEditor::SyntaxHighlighterRunner *highlighter = doc->syntaxHighlighterRunner())
+        if (TextEditor::SyntaxHighlighter *highlighter = doc->syntaxHighlighter())
             highlighter->clearAllExtraFormats();
     }
 }
@@ -413,7 +413,7 @@ void SemanticTokenSupport::highlight(const Utils::FilePath &filePath, bool force
     TextDocument *doc = TextDocument::textDocumentForFilePath(filePath);
     if (!doc || LanguageClientManager::clientForDocument(doc) != m_client)
         return;
-    SyntaxHighlighterRunner *highlighter = doc->syntaxHighlighterRunner();
+    SyntaxHighlighter *highlighter = doc->syntaxHighlighter();
     if (!highlighter)
         return;
     const VersionedTokens versionedTokens = m_tokens.value(filePath);
diff --git a/src/plugins/qmljseditor/qmljssemantichighlighter.cpp b/src/plugins/qmljseditor/qmljssemantichighlighter.cpp
index c414684df7a..67e14dfbcd5 100644
--- a/src/plugins/qmljseditor/qmljssemantichighlighter.cpp
+++ b/src/plugins/qmljseditor/qmljssemantichighlighter.cpp
@@ -569,7 +569,7 @@ void SemanticHighlighter::applyResults(int from, int to)
 
     if (m_enableHighlighting)
         TextEditor::SemanticHighlighter::incrementalApplyExtraAdditionalFormats(
-            m_document->syntaxHighlighterRunner(), m_watcher.future(), from, to, m_extraFormats);
+            m_document->syntaxHighlighter(), m_watcher.future(), from, to, m_extraFormats);
 }
 
 void SemanticHighlighter::finished()
@@ -584,7 +584,7 @@ void SemanticHighlighter::finished()
 
     if (m_enableHighlighting)
         TextEditor::SemanticHighlighter::clearExtraAdditionalFormatsUntilEnd(
-            m_document->syntaxHighlighterRunner(), m_watcher.future());
+            m_document->syntaxHighlighter(), m_watcher.future());
 }
 
 void SemanticHighlighter::run(QPromise<Use> &promise,
diff --git a/src/plugins/texteditor/CMakeLists.txt b/src/plugins/texteditor/CMakeLists.txt
index c36d4121ece..e766ec06a10 100644
--- a/src/plugins/texteditor/CMakeLists.txt
+++ b/src/plugins/texteditor/CMakeLists.txt
@@ -96,7 +96,6 @@ add_qtc_plugin(TextEditor
     snippets/snippetssettingspage.cpp snippets/snippetssettingspage.h
     storagesettings.cpp storagesettings.h
     syntaxhighlighter.cpp syntaxhighlighter.h
-    syntaxhighlighterrunner.cpp syntaxhighlighterrunner.h
     tabsettings.cpp tabsettings.h
     tabsettingswidget.cpp tabsettingswidget.h
     textdocument.cpp textdocument.h
diff --git a/src/plugins/texteditor/highlighter_test.cpp b/src/plugins/texteditor/highlighter_test.cpp
index d50c560e23a..2cbd2b75d57 100644
--- a/src/plugins/texteditor/highlighter_test.cpp
+++ b/src/plugins/texteditor/highlighter_test.cpp
@@ -1,11 +1,10 @@
 // Copyright (C) 2023 The Qt Company Ltd.
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
 
-#include "syntaxhighlighterrunner.h"
-
 #include "highlighter_test.h"
 
 #include "fontsettings.h"
+#include "syntaxhighlighter.h"
 #include "textdocument.h"
 #include "texteditor.h"
 #include "texteditorsettings.h"
@@ -61,7 +60,7 @@ void GenerigHighlighterTests::initTestCase()
     m_editor->editorWidget()->configureGenericHighlighter(
         Utils::mimeTypeForName(Utils::Constants::JSON_MIMETYPE));
     QVERIFY(m_editor);
-    m_editor->textDocument()->syntaxHighlighterRunner()->rehighlight();
+    m_editor->textDocument()->syntaxHighlighter()->rehighlight();
 }
 
 using FormatRanges = QList<QTextLayout::FormatRange>;
@@ -214,7 +213,7 @@ void GenerigHighlighterTests::testPreeditText()
     block.layout()->setPreeditArea(7, "uaf");
     c.endEditBlock();
 
-    m_editor->textDocument()->syntaxHighlighterRunner()->rehighlight();
+    m_editor->textDocument()->syntaxHighlighter()->rehighlight();
 
     const FormatRanges formatRanges = {{0, 4, toFormat(C_VISUAL_WHITESPACE)},
                                        {4, 3, toFormat(C_TYPE)},
diff --git a/src/plugins/texteditor/highlighterhelper.cpp b/src/plugins/texteditor/highlighterhelper.cpp
index 6aa98439c05..e25b935f8ac 100644
--- a/src/plugins/texteditor/highlighterhelper.cpp
+++ b/src/plugins/texteditor/highlighterhelper.cpp
@@ -9,7 +9,6 @@
 #include "texteditor.h"
 #include "texteditorsettings.h"
 #include "texteditortr.h"
-#include "syntaxhighlighterrunner.h"
 
 #include <coreplugin/editormanager/documentmodel.h>
 #include <coreplugin/icore.h>
@@ -210,8 +209,8 @@ void reload()
     highlightRepository()->reload();
     for (auto editor : Core::DocumentModel::editorsForOpenedDocuments()) {
         if (auto textEditor = qobject_cast<BaseTextEditor *>(editor)) {
-            if (auto highlighterRunner = textEditor->textDocument()->syntaxHighlighterRunner();
-                highlighterRunner && highlighterRunner->useGenericHighlighter()) {
+            if (auto highlighter = textEditor->textDocument()->syntaxHighlighter();
+                highlighter && qobject_cast<SyntaxHighlighter*>(highlighter)) {
                 textEditor->editorWidget()->configureGenericHighlighter();
             }
         }
diff --git a/src/plugins/texteditor/semantichighlighter.cpp b/src/plugins/texteditor/semantichighlighter.cpp
index 9cee346d8b0..0c385d2e4b5 100644
--- a/src/plugins/texteditor/semantichighlighter.cpp
+++ b/src/plugins/texteditor/semantichighlighter.cpp
@@ -5,7 +5,6 @@
 
 #include "syntaxhighlighter.h"
 #include "texteditorsettings.h"
-#include "syntaxhighlighterrunner.h"
 
 #include <utils/qtcassert.h>
 
@@ -75,7 +74,7 @@ const Ranges rangesForResult(
 }
 
 void SemanticHighlighter::incrementalApplyExtraAdditionalFormats(
-    SyntaxHighlighterRunner *highlighter,
+    SyntaxHighlighter *highlighter,
     const QFuture<HighlightingResult> &future,
     int from,
     int to,
@@ -114,21 +113,17 @@ void SemanticHighlighter::incrementalApplyExtraAdditionalFormats(
             formatRanges[range.block].append(range.formatRange);
     }
 
-    QList<int> clearBlockNumberVector;
-    QMap<int, QList<QTextLayout::FormatRange>> blockNumberMap;
     for (auto &[block, ranges] : formatRanges) {
         while (currentBlock < block) {
-            clearBlockNumberVector.append(currentBlock.blockNumber());
+            highlighter->clearExtraFormats(currentBlock);
             currentBlock = currentBlock.next();
         }
-        blockNumberMap[block.blockNumber()] = ranges;
+        highlighter->setExtraFormats(block, std::move(ranges));
         currentBlock = block.next();
     }
-    highlighter->clearExtraFormats(clearBlockNumberVector);
-    highlighter->setExtraFormats(blockNumberMap);
 }
 
-void SemanticHighlighter::setExtraAdditionalFormats(SyntaxHighlighterRunner *highlighter,
+void SemanticHighlighter::setExtraAdditionalFormats(SyntaxHighlighter *highlighter,
                                                     const QList<HighlightingResult> &results,
                                                     const QHash<int, QTextCharFormat> &kindToFormat)
 {
@@ -139,19 +134,19 @@ void SemanticHighlighter::setExtraAdditionalFormats(SyntaxHighlighterRunner *hig
     QTextDocument *doc = highlighter->document();
     QTC_ASSERT(doc, return );
 
-    QMap<int, QList<QTextLayout::FormatRange>> blockNumberMap;
+    std::map<QTextBlock, QVector<QTextLayout::FormatRange>> formatRanges;
 
-    for (const HighlightingResult &result : results) {
-        const Ranges ranges = rangesForResult(result, doc, kindToFormat);
-        for (const Range &range : ranges)
-            blockNumberMap[range.block.blockNumber()].append(range.formatRange);
+    for (auto result : results) {
+        for (const Range &range : rangesForResult(result, doc, kindToFormat))
+            formatRanges[range.block].append(range.formatRange);
     }
 
-    highlighter->setExtraFormats(blockNumberMap);
+    for (auto &[block, ranges] : formatRanges)
+        highlighter->setExtraFormats(block, std::move(ranges));
 }
 
 void SemanticHighlighter::clearExtraAdditionalFormatsUntilEnd(
-    SyntaxHighlighterRunner *highlighter, const QFuture<HighlightingResult> &future)
+    SyntaxHighlighter *highlighter, const QFuture<HighlightingResult> &future)
 {
     const QTextDocument * const doc = highlighter->document();
     QTextBlock firstBlockToClear = doc->begin();
@@ -168,7 +163,6 @@ void SemanticHighlighter::clearExtraAdditionalFormatsUntilEnd(
 
     QList<int> clearBlockNumberVector;
     for (QTextBlock b = firstBlockToClear; b.isValid(); b = b.next())
-        clearBlockNumberVector.append(b.blockNumber());
+        highlighter->clearExtraFormats(b);
 
-    highlighter->clearExtraFormats(clearBlockNumberVector);
 }
diff --git a/src/plugins/texteditor/semantichighlighter.h b/src/plugins/texteditor/semantichighlighter.h
index ad1d854b834..f8ae30a0eda 100644
--- a/src/plugins/texteditor/semantichighlighter.h
+++ b/src/plugins/texteditor/semantichighlighter.h
@@ -21,7 +21,6 @@ QT_END_NAMESPACE
 namespace TextEditor {
 
 class SyntaxHighlighter;
-class SyntaxHighlighterRunner;
 
 class TEXTEDITOR_EXPORT HighlightingResult
 {
@@ -74,7 +73,7 @@ using Splitter = std::function<const QList<std::pair<HighlightingResult, QTextBl
 // the (to-1).line result.
 // Requires that results of the Future are ordered by line.
 void TEXTEDITOR_EXPORT
-incrementalApplyExtraAdditionalFormats(SyntaxHighlighterRunner *highlighter,
+incrementalApplyExtraAdditionalFormats(SyntaxHighlighter *highlighter,
                                        const QFuture<HighlightingResult> &future,
                                        int from,
                                        int to,
@@ -85,7 +84,7 @@ incrementalApplyExtraAdditionalFormats(SyntaxHighlighterRunner *highlighter,
 // indicated by Result::kind and kindToFormat to the correct location using
 // SyntaxHighlighter::setExtraFormats. In contrast to
 // incrementalApplyExtraAdditionalFormats the results do not have to be ordered by line.
-void TEXTEDITOR_EXPORT setExtraAdditionalFormats(SyntaxHighlighterRunner *highlighter,
+void TEXTEDITOR_EXPORT setExtraAdditionalFormats(SyntaxHighlighter *highlighter,
                                                  const HighlightingResults &results,
                                                  const QHash<int, QTextCharFormat> &kindToFormat);
 
@@ -93,7 +92,7 @@ void TEXTEDITOR_EXPORT setExtraAdditionalFormats(SyntaxHighlighterRunner *highli
 // until the end of the document.
 // Requires that results of the Future are ordered by line.
 void TEXTEDITOR_EXPORT clearExtraAdditionalFormatsUntilEnd(
-    SyntaxHighlighterRunner *highlighter, const QFuture<HighlightingResult> &future);
+    SyntaxHighlighter *highlighter, const QFuture<HighlightingResult> &future);
 
 } // namespace SemanticHighlighter
 } // namespace TextEditor
diff --git a/src/plugins/texteditor/syntaxhighlighter.cpp b/src/plugins/texteditor/syntaxhighlighter.cpp
index f7db190852d..0162cdeeff0 100644
--- a/src/plugins/texteditor/syntaxhighlighter.cpp
+++ b/src/plugins/texteditor/syntaxhighlighter.cpp
@@ -25,8 +25,6 @@ enum HighlighterTypeProperty
 
 class SyntaxHighlighterPrivate
 {
-    SyntaxHighlighter *q_ptr = nullptr;
-    Q_DECLARE_PUBLIC(SyntaxHighlighter)
 public:
     SyntaxHighlighterPrivate() = default;
 
@@ -37,8 +35,10 @@ public:
 
     QPointer<QTextDocument> doc;
 
+    void updateFormats(int from, int charsRemoved, int charsAdded);
     void reformatBlocks(int from, int charsRemoved, int charsAdded);
-    void reformatBlock(const QTextBlock &block, int from, int charsRemoved, int charsAdded);
+    void reformatBlocks();
+    void reformatBlock(const QTextBlock &block);
 
     inline void rehighlight(QTextCursor &cursor, QTextCursor::MoveOperation operation) {
         inReformatBlocks = true;
@@ -48,7 +48,7 @@ public:
         inReformatBlocks = false;
     }
 
-    void applyFormatChanges(int from, int charsRemoved, int charsAdded);
+    void applyFormatChanges();
     void updateFormats(const FontSettings &fontSettings);
 
     FontSettings fontSettings;
@@ -61,6 +61,11 @@ public:
     QList<std::pair<int,TextStyle>> formatCategories;
     QTextCharFormat whitespaceFormat;
     QString mimeType;
+    bool syntaxInfoUpToDate = false;
+    int highlightStartBlock = 0;
+    int highlightEndBlock = 0;
+    QSet<int> forceRehighlightBlocks;
+    SyntaxHighlighter *q;
 };
 
 static bool adjustRange(QTextLayout::FormatRange &range, int from, int charsDelta)
@@ -77,31 +82,30 @@ static bool adjustRange(QTextLayout::FormatRange &range, int from, int charsDelt
 
 void SyntaxHighlighter::delayedRehighlight()
 {
-    Q_D(SyntaxHighlighter);
     if (!d->rehighlightPending)
         return;
     d->rehighlightPending = false;
 
-    if (document()->isEmpty())
-        return;
-
     rehighlight();
 }
 
+void SyntaxHighlighter::continueRehighlight()
+{
+    d->reformatBlocks();
+}
+
 #ifdef WITH_TESTS
 SyntaxHighlighter::SyntaxHighlighter(QTextDocument *parent, const FontSettings &fontsettings)
-    : QObject(parent), d_ptr(new SyntaxHighlighterPrivate(fontsettings))
+    : QObject(parent), d(new SyntaxHighlighterPrivate(fontsettings))
 {
-    d_ptr->q_ptr = this;
+    d->q = this;
     if (parent)
         setDocument(parent);
 }
 #endif
 
-void SyntaxHighlighterPrivate::applyFormatChanges(int from, int charsRemoved, int charsAdded)
+void SyntaxHighlighterPrivate::applyFormatChanges()
 {
-    bool formatsChanged = false;
-
     QTextLayout *layout = currentBlock.layout();
 
     QList<QTextLayout::FormatRange> ranges;
@@ -111,12 +115,6 @@ void SyntaxHighlighterPrivate::applyFormatChanges(int from, int charsRemoved, in
               return range.format.property(SyntaxHighlight).toBool();
           });
 
-    if (currentBlock.contains(from)) {
-        const int charsDelta = charsAdded - charsRemoved;
-        for (QTextLayout::FormatRange &range : ranges)
-            formatsChanged |= adjustRange(range, from - currentBlock.position(), charsDelta);
-    }
-
     QTextCharFormat emptyFormat;
 
     QTextLayout::FormatRange r;
@@ -157,7 +155,7 @@ void SyntaxHighlighterPrivate::applyFormatChanges(int from, int charsRemoved, in
         newRanges << r;
     }
 
-    formatsChanged = formatsChanged || (newRanges.size() != oldRanges.size());
+    bool formatsChanged = (newRanges.size() != oldRanges.size());
 
     for (int i = 0; !formatsChanged && i < newRanges.size(); ++i) {
         const QTextLayout::FormatRange &o = oldRanges.at(i);
@@ -174,85 +172,103 @@ void SyntaxHighlighterPrivate::applyFormatChanges(int from, int charsRemoved, in
 
 void SyntaxHighlighter::reformatBlocks(int from, int charsRemoved, int charsAdded)
 {
-    Q_D(SyntaxHighlighter);
     if (!d->inReformatBlocks)
         d->reformatBlocks(from, charsRemoved, charsAdded);
 }
 
+void SyntaxHighlighterPrivate::updateFormats(int from, int charsRemoved, int charsAdded)
+{
+    bool formatsChanged = false;
+
+    const QTextBlock block = doc->findBlock(from);
+    QTextLayout *layout = block.layout();
+
+    QList<QTextLayout::FormatRange> ranges = layout->formats();
+
+    const int charsDelta = charsAdded - charsRemoved;
+    for (QTextLayout::FormatRange &range : ranges)
+        formatsChanged |= adjustRange(range, from - block.position(), charsDelta);
+
+    if (formatsChanged) {
+        layout->setFormats(ranges);
+        doc->markContentsDirty(block.position(), block.length());
+    }
+}
+
 void SyntaxHighlighterPrivate::reformatBlocks(int from, int charsRemoved, int charsAdded)
 {
-    Q_Q(SyntaxHighlighter);
-    foldValidator.reset();
-
-    rehighlightPending = false;
+    updateFormats(from, charsRemoved, charsAdded);
 
     QTextBlock block = doc->findBlock(from);
+    if (block.isValid() && block.blockNumber() < highlightStartBlock)
+        highlightStartBlock = block.blockNumber();
+    block = doc->findBlock(from + charsAdded + (charsRemoved > 0 ? 1 : 0));
     if (!block.isValid())
-        return;
+        highlightEndBlock = doc->blockCount() - 1;
+    else if (block.blockNumber() > highlightEndBlock)
+        highlightEndBlock = block.blockNumber();
 
-    int endPosition;
-    QTextBlock lastBlock = doc->findBlock(from + charsAdded + (charsRemoved > 0 ? 1 : 0));
-    if (lastBlock.isValid())
-        endPosition = lastBlock.position() + lastBlock.length();
-    else
-        endPosition = doc->lastBlock().position() + doc->lastBlock().length();
+    reformatBlocks();
+}
+
+void SyntaxHighlighterPrivate::reformatBlocks()
+{
+    QElapsedTimer et;
+    et.start();
+
+    syntaxInfoUpToDate = false;
+    rehighlightPending = false;
+
+    foldValidator.reset();
 
     bool forceHighlightOfNextBlock = false;
+    QTextBlock block = doc->findBlockByNumber(highlightStartBlock);
+    QTC_ASSERT(block.isValid(), block = doc->firstBlock());
+    QTextBlock endBlock = doc->findBlockByNumber(highlightEndBlock);
+    QTC_ASSERT(endBlock.isValid(), endBlock = doc->lastBlock());
 
-    QList<SyntaxHighlighter::Result> vecRes;
-
-    SyntaxHighlighter::Result resStart;
-    resStart.m_state = SyntaxHighlighter::State::Start;
-    vecRes << resStart;
-
-    while (block.isValid() && (block.position() < endPosition || forceHighlightOfNextBlock)) {
-        if (QThread::currentThread()->isInterruptionRequested() || q->isInterrupted()) {
-            inReformatBlocks = false;
-            emit q->resultsReady({});
-            return;
-        }
+    while (block.isValid()) {
+        if (et.elapsed() > 20)
+            break;
 
         const int stateBeforeHighlight = block.userState();
 
-        reformatBlock(block, from, charsRemoved, charsAdded);
-
-        forceHighlightOfNextBlock = (block.userState() != stateBeforeHighlight);
-
-        SyntaxHighlighter::Result res;
-        res.m_formatRanges = block.layout()->formats();
-        res.fillByBlock(block);
-        vecRes << res;
-
-        // Sending data to the text editor in chunks of 200 blocks is a sensible approach.
-        // This helps avoid UI slowdowns when applying formatting to the text.
-        if (vecRes.size() >= 200) {
-            emit q->resultsReady(vecRes);
-            vecRes.clear();
+        if (forceHighlightOfNextBlock || forceRehighlightBlocks.contains(block.blockNumber())
+                || block.blockNumber() <= highlightEndBlock) {
+            reformatBlock(block);
+            forceRehighlightBlocks.remove(block.blockNumber());
+            forceHighlightOfNextBlock = (block.userState() != stateBeforeHighlight);
         }
+        highlightStartBlock = block.blockNumber();
 
+        if (block == endBlock && !forceHighlightOfNextBlock)
+            break;
         block = block.next();
     }
 
     formatChanges.clear();
-
     foldValidator.finalize();
-    SyntaxHighlighter::Result res;
-    res.m_state = SyntaxHighlighter::State::Done;
-    vecRes << res;
-    emit q->resultsReady(vecRes);
+
+    if (endBlock.isValid() && block.isValid() && block.blockNumber() < endBlock.blockNumber()) {
+        QMetaObject::invokeMethod(q, &SyntaxHighlighter::continueRehighlight, Qt::QueuedConnection);
+        if (forceHighlightOfNextBlock)
+            forceRehighlightBlocks << block.blockNumber();
+    } else {
+        highlightEndBlock = 0;
+        syntaxInfoUpToDate = true;
+        emit q->finished();
+    }
 }
 
-void SyntaxHighlighterPrivate::reformatBlock(const QTextBlock &block, int from, int charsRemoved, int charsAdded)
+void SyntaxHighlighterPrivate::reformatBlock(const QTextBlock &block)
 {
-    Q_Q(SyntaxHighlighter);
-
-    Q_ASSERT_X(!currentBlock.isValid(), "SyntaxHighlighter::reformatBlock()", "reFormatBlock() called recursively");
+    QTC_ASSERT(!currentBlock.isValid(), return);
 
     currentBlock = block;
 
     formatChanges.fill(QTextCharFormat(), block.length() - 1);
     q->highlightBlock(block.text());
-    applyFormatChanges(from, charsRemoved, charsAdded);
+    applyFormatChanges();
 
     foldValidator.process(currentBlock);
 
@@ -293,9 +309,9 @@ void SyntaxHighlighterPrivate::reformatBlock(const QTextBlock &block, int from,
     Constructs a SyntaxHighlighter with the given \a parent.
 */
 SyntaxHighlighter::SyntaxHighlighter(QObject *parent)
-    : QObject(parent), d_ptr(new SyntaxHighlighterPrivate)
+    : QObject(parent), d(new SyntaxHighlighterPrivate)
 {
-    d_ptr->q_ptr = this;
+    d->q = this;
 }
 
 /*!
@@ -304,9 +320,9 @@ SyntaxHighlighter::SyntaxHighlighter(QObject *parent)
     SyntaxHighlighter.
 */
 SyntaxHighlighter::SyntaxHighlighter(QTextDocument *parent)
-    : QObject(parent), d_ptr(new SyntaxHighlighterPrivate)
+    : QObject(parent), d(new SyntaxHighlighterPrivate)
 {
-    d_ptr->q_ptr = this;
+    d->q = this;
     if (parent)
         setDocument(parent);
 }
@@ -317,9 +333,9 @@ SyntaxHighlighter::SyntaxHighlighter(QTextDocument *parent)
     the SyntaxHighlighter.
 */
 SyntaxHighlighter::SyntaxHighlighter(QTextEdit *parent)
-    : QObject(parent), d_ptr(new SyntaxHighlighterPrivate)
+    : QObject(parent), d(new SyntaxHighlighterPrivate)
 {
-    d_ptr->q_ptr = this;
+    d->q = this;
     if (parent)
         setDocument(parent->document());
 }
@@ -338,7 +354,6 @@ SyntaxHighlighter::~SyntaxHighlighter()
 */
 void SyntaxHighlighter::setDocument(QTextDocument *doc)
 {
-    Q_D(SyntaxHighlighter);
     if (d->doc == doc)
         return;
 
@@ -356,10 +371,7 @@ void SyntaxHighlighter::setDocument(QTextDocument *doc)
     documentChanged(oldDoc, d->doc);
     if (d->doc) {
         connect(d->doc, &QTextDocument::contentsChange, this, &SyntaxHighlighter::reformatBlocks);
-        d->rehighlightPending = true;
-        QMetaObject::invokeMethod(this,
-                                  &SyntaxHighlighter::delayedRehighlight,
-                                  Qt::QueuedConnection);
+        scheduleRehighlight();
         d->foldValidator.setup(qobject_cast<TextDocumentLayout *>(doc->documentLayout()));
     }
 }
@@ -370,19 +382,16 @@ void SyntaxHighlighter::setDocument(QTextDocument *doc)
 */
 QTextDocument *SyntaxHighlighter::document() const
 {
-    Q_D(const SyntaxHighlighter);
     return d->doc;
 }
 
 void SyntaxHighlighter::setMimeType(const QString &mimeType)
 {
-    Q_D(SyntaxHighlighter);
     d->mimeType = mimeType;
 }
 
 QString SyntaxHighlighter::mimeType() const
 {
-    Q_D(const SyntaxHighlighter);
     return d->mimeType;
 }
 
@@ -395,7 +404,6 @@ QString SyntaxHighlighter::mimeType() const
 */
 void SyntaxHighlighter::rehighlight()
 {
-    Q_D(SyntaxHighlighter);
     if (!d->doc)
         return;
 
@@ -403,6 +411,17 @@ void SyntaxHighlighter::rehighlight()
     d->rehighlight(cursor, QTextCursor::End);
 }
 
+void SyntaxHighlighter::scheduleRehighlight()
+{
+    if (d->rehighlightPending)
+        return;
+    d->rehighlightPending = true;
+    d->syntaxInfoUpToDate = false;
+    QMetaObject::invokeMethod(this,
+                              &SyntaxHighlighter::delayedRehighlight,
+                              Qt::QueuedConnection);
+}
+
 /*!
     \since 4.6
 
@@ -412,7 +431,6 @@ void SyntaxHighlighter::rehighlight()
 */
 void SyntaxHighlighter::rehighlightBlock(const QTextBlock &block)
 {
-    Q_D(SyntaxHighlighter);
     if (!d->doc || !block.isValid() || block.document() != d->doc)
         return;
 
@@ -486,7 +504,6 @@ void SyntaxHighlighter::rehighlightBlock(const QTextBlock &block)
 */
 void SyntaxHighlighter::setFormat(int start, int count, const QTextCharFormat &format)
 {
-    Q_D(SyntaxHighlighter);
     if (start < 0 || start >= d->formatChanges.count())
         return;
 
@@ -533,7 +550,6 @@ void SyntaxHighlighter::setFormat(int start, int count, const QFont &font)
 
 void SyntaxHighlighter::formatSpaces(const QString &text, int start, int count)
 {
-    Q_D(const SyntaxHighlighter);
     int offset = start;
     const int end = std::min(start + count, int(text.length()));
     while (offset < end) {
@@ -585,10 +601,7 @@ void SyntaxHighlighter::setFormatWithSpaces(const QString &text, int start, int
 */
 QTextCharFormat SyntaxHighlighter::format(int pos) const
 {
-    Q_D(const SyntaxHighlighter);
-    if (pos < 0 || pos >= d->formatChanges.count())
-        return QTextCharFormat();
-    return d->formatChanges.at(pos);
+    return d->formatChanges.value(pos);
 }
 
 /*!
@@ -600,7 +613,6 @@ QTextCharFormat SyntaxHighlighter::format(int pos) const
 */
 int SyntaxHighlighter::previousBlockState() const
 {
-    Q_D(const SyntaxHighlighter);
     if (!d->currentBlock.isValid())
         return -1;
 
@@ -617,7 +629,6 @@ int SyntaxHighlighter::previousBlockState() const
 */
 int SyntaxHighlighter::currentBlockState() const
 {
-    Q_D(const SyntaxHighlighter);
     if (!d->currentBlock.isValid())
         return -1;
 
@@ -631,7 +642,6 @@ int SyntaxHighlighter::currentBlockState() const
 */
 void SyntaxHighlighter::setCurrentBlockState(int newState)
 {
-    Q_D(SyntaxHighlighter);
     if (!d->currentBlock.isValid())
         return;
 
@@ -674,7 +684,6 @@ void SyntaxHighlighter::setCurrentBlockState(int newState)
 */
 void SyntaxHighlighter::setCurrentBlockUserData(QTextBlockUserData *data)
 {
-    Q_D(SyntaxHighlighter);
     if (!d->currentBlock.isValid())
         return;
 
@@ -689,7 +698,6 @@ void SyntaxHighlighter::setCurrentBlockUserData(QTextBlockUserData *data)
 */
 QTextBlockUserData *SyntaxHighlighter::currentBlockUserData() const
 {
-    Q_D(const SyntaxHighlighter);
     if (!d->currentBlock.isValid())
         return nullptr;
 
@@ -703,7 +711,6 @@ QTextBlockUserData *SyntaxHighlighter::currentBlockUserData() const
 */
 QTextBlock SyntaxHighlighter::currentBlock() const
 {
-    Q_D(const SyntaxHighlighter);
     return d->currentBlock;
 }
 
@@ -715,8 +722,6 @@ static bool byStartOfRange(const QTextLayout::FormatRange &range, const QTextLay
 void SyntaxHighlighter::setExtraFormats(const QTextBlock &block,
                                         const QList<QTextLayout::FormatRange> &formats)
 {
-    Q_D(SyntaxHighlighter);
-
     QList<QTextLayout::FormatRange> formatsCopy = formats;
 
     const int blockLength = block.length();
@@ -766,20 +771,17 @@ void SyntaxHighlighter::setExtraFormats(const QTextBlock &block,
     d->inReformatBlocks = true;
     block.layout()->setFormats(formatsToApply);
 
-    SyntaxHighlighter::Result res;
-    res.m_formatRanges = block.layout()->formats();
-    res.fillByBlock(block);
-    res.m_state = SyntaxHighlighter::State::Extras;
-    emit resultsReady({std::move(res)});
-
     document()->markContentsDirty(block.position(), blockLength - 1);
     d->inReformatBlocks = wasInReformatBlocks;
 }
 
+bool SyntaxHighlighter::syntaxHighlighterUpToDate() const
+{
+    return d->syntaxInfoUpToDate;
+}
+
 void SyntaxHighlighter::clearExtraFormats(const QTextBlock &block)
 {
-    Q_D(SyntaxHighlighter);
-
     const int blockLength = block.length();
     if (block.layout() == nullptr || blockLength == 0)
         return;
@@ -793,12 +795,6 @@ void SyntaxHighlighter::clearExtraFormats(const QTextBlock &block)
     d->inReformatBlocks = true;
     block.layout()->setFormats(formatsToApply);
 
-    SyntaxHighlighter::Result res;
-    res.m_formatRanges = block.layout()->formats();
-    res.fillByBlock(block);
-    res.m_state = SyntaxHighlighter::State::Extras;
-    emit resultsReady({std::move(res)});
-
     document()->markContentsDirty(block.position(), blockLength - 1);
     d->inReformatBlocks = wasInReformatBlocks;
 }
@@ -848,13 +844,11 @@ QList<QColor> SyntaxHighlighter::generateColors(int n, const QColor &background)
 
 void SyntaxHighlighter::setFontSettings(const FontSettings &fontSettings)
 {
-    Q_D(SyntaxHighlighter);
     d->updateFormats(fontSettings);
 }
 
 FontSettings SyntaxHighlighter::fontSettings() const
 {
-    Q_D(const SyntaxHighlighter);
     return d->fontSettings;
 }
 
@@ -897,7 +891,6 @@ void SyntaxHighlighter::setTextFormatCategories(int count,
 */
 void SyntaxHighlighter::setTextFormatCategories(const QList<std::pair<int, TextStyle>> &categories)
 {
-    Q_D(SyntaxHighlighter);
     d->formatCategories = categories;
     const int maxCategory = Utils::maxElementOr(categories, {-1, C_TEXT}).first;
     d->formats = QList<QTextCharFormat>(maxCategory + 1);
@@ -906,7 +899,6 @@ void SyntaxHighlighter::setTextFormatCategories(const QList<std::pair<int, TextS
 
 QTextCharFormat SyntaxHighlighter::formatForCategory(int category) const
 {
-    Q_D(const SyntaxHighlighter);
     QTC_ASSERT(d->formats.size() > category, return QTextCharFormat());
 
     return d->formats.at(category);
@@ -914,7 +906,6 @@ QTextCharFormat SyntaxHighlighter::formatForCategory(int category) const
 
 QTextCharFormat SyntaxHighlighter::whitespacified(const QTextCharFormat &fmt)
 {
-    Q_D(SyntaxHighlighter);
     QTextCharFormat format = d->whitespaceFormat;
     format.setBackground(fmt.background());
     return format;
diff --git a/src/plugins/texteditor/syntaxhighlighter.h b/src/plugins/texteditor/syntaxhighlighter.h
index 6b07d333f33..f5506374267 100644
--- a/src/plugins/texteditor/syntaxhighlighter.h
+++ b/src/plugins/texteditor/syntaxhighlighter.h
@@ -34,7 +34,6 @@ class SyntaxHighlighterPrivate;
 class TEXTEDITOR_EXPORT SyntaxHighlighter : public QObject
 {
     Q_OBJECT
-    Q_DECLARE_PRIVATE(SyntaxHighlighter)
 public:
     SyntaxHighlighter(QObject *parent = nullptr);
     SyntaxHighlighter(QTextDocument *parent);
@@ -53,79 +52,16 @@ public:
     virtual void setFontSettings(const TextEditor::FontSettings &fontSettings);
     TextEditor::FontSettings fontSettings() const;
 
-    enum State {
-        Start,
-        InProgress,
-        Done,
-        Extras
-    };
-
-    struct Result
-    {
-        void fillByBlock(const QTextBlock &block)
-        {
-            m_blockNumber = block.blockNumber();
-            m_userState = block.userState();
-
-            TextBlockUserData *userDate = TextDocumentLayout::textUserData(block);
-            if (!userDate)
-                return;
-
-            m_hasBlockUserData = true;
-            m_foldingIndent = userDate->foldingIndent();
-            m_ifdefedOut = userDate->ifdefedOut();
-            m_foldingStartIncluded = userDate->foldingStartIncluded();
-            m_foldingEndIncluded = userDate->foldingEndIncluded();
-            m_parentheses = userDate->parentheses();
-            m_expectedRawStringSuffix = userDate->expectedRawStringSuffix();
-        }
-
-        void copyToBlock(QTextBlock &block) const
-        {
-            block.setUserState(m_userState);
-
-            if (!m_hasBlockUserData)
-                return;
-
-            TextBlockUserData *data = TextDocumentLayout::userData(block);
-            data->setExpectedRawStringSuffix(m_expectedRawStringSuffix);
-            data->setFoldingIndent(m_foldingIndent);
-            data->setFoldingStartIncluded(m_foldingStartIncluded);
-            data->setFoldingEndIncluded(m_foldingEndIncluded);
-
-            if (m_ifdefedOut)
-                data->setIfdefedOut();
-            else
-                data->clearIfdefedOut();
-
-            data->setParentheses(m_parentheses);
-        }
-
-        int m_blockNumber;
-        bool m_hasBlockUserData = false;
-
-        int m_foldingIndent : 16;
-        uint m_ifdefedOut : 1;
-        uint m_foldingStartIncluded : 1;
-        uint m_foldingEndIncluded : 1;
-
-        Parentheses m_parentheses;
-        QByteArray m_expectedRawStringSuffix;
-        int m_userState = -1;
-        QList<QTextLayout::FormatRange> m_formatRanges;
-
-        State m_state = InProgress;
-    };
-
-    void setInterrupted(bool interrupted) { m_interrupted = interrupted; }
-    bool isInterrupted() { return m_interrupted; }
     void setExtraFormats(const QTextBlock &block, const QList<QTextLayout::FormatRange> &formats);
     virtual void setLanguageFeaturesFlags(unsigned int /*flags*/) {}; // needed for CppHighlighting
     virtual void setEnabled(bool /*enabled*/) {}; // needed for DiffAndLogHighlighter
     virtual void setDefinitionName(const QString & /*definitionName*/) {} // needed for Highlighter
 
+    bool syntaxHighlighterUpToDate() const;
+
 public slots:
     virtual void rehighlight();
+    virtual void scheduleRehighlight();
     void rehighlightBlock(const QTextBlock &block);
     void clearExtraFormats(const QTextBlock &block);
     void reformatBlocks(int from, int charsRemoved, int charsAdded);
@@ -160,18 +96,18 @@ protected:
 
     QTextBlock currentBlock() const;
 
-protected:
     virtual void documentChanged(QTextDocument * /*oldDoc*/, QTextDocument * /*newDoc*/) {};
 
 signals:
-    void resultsReady(const QList<Result> &result);
+    void finished();
 
 private:
     void setTextFormatCategories(const QList<std::pair<int, TextStyle>> &categories);
     void delayedRehighlight();
+    void continueRehighlight();
 
-    QScopedPointer<SyntaxHighlighterPrivate> d_ptr;
-    std::atomic<bool> m_interrupted = false;
+    friend class SyntaxHighlighterPrivate;
+    std::unique_ptr<SyntaxHighlighterPrivate> d;
 
 #ifdef WITH_TESTS
     friend class tst_highlighter;
diff --git a/src/plugins/texteditor/syntaxhighlighterrunner.cpp b/src/plugins/texteditor/syntaxhighlighterrunner.cpp
deleted file mode 100644
index 874f8254abf..00000000000
--- a/src/plugins/texteditor/syntaxhighlighterrunner.cpp
+++ /dev/null
@@ -1,385 +0,0 @@
-// Copyright (C) 2023 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
-
-#include "syntaxhighlighterrunner.h"
-
-#include "fontsettings.h"
-#include "textdocumentlayout.h"
-#include "texteditorsettings.h"
-#include "highlighter.h"
-
-#include <utils/algorithm.h>
-#include <utils/textutils.h>
-
-#include <QMetaObject>
-#include <QTextCursor>
-#include <QTextDocument>
-#include <QThread>
-
-namespace TextEditor {
-
-struct BlockPreeditData {
-    int position;
-    QString text;
-};
-
-class SyntaxHighlighterRunnerPrivate : public QObject
-{
-    Q_OBJECT
-public:
-    SyntaxHighlighterRunnerPrivate(SyntaxHighlighter *highlighter,
-                                   QTextDocument *document,
-                                   bool async)
-        : m_highlighter(highlighter)
-    {
-        if (async) {
-            m_document = new QTextDocument(this);
-            m_document->setDocumentLayout(new TextDocumentLayout(m_document));
-        } else {
-            m_document = document;
-        }
-
-        m_highlighter->setParent(m_document);
-        m_highlighter->setDocument(m_document);
-
-        connect(m_highlighter,
-                &SyntaxHighlighter::resultsReady,
-                this,
-                &SyntaxHighlighterRunnerPrivate::resultsReady);
-    }
-
-    void changeDocument(int from,
-                        int charsRemoved,
-                        const QString textAdded,
-                        const QMap<int, BlockPreeditData> &blocksPreedit)
-    {
-        QTextCursor cursor(m_document);
-        cursor.setPosition(qMin(m_document->characterCount() - 1, from + charsRemoved));
-        cursor.setPosition(from, QTextCursor::KeepAnchor);
-        cursor.insertText(textAdded);
-
-        for (auto it = blocksPreedit.cbegin(); it != blocksPreedit.cend(); ++it) {
-            const QTextBlock block = m_document->findBlockByNumber(it.key());
-            block.layout()->setPreeditArea(it.value().position, it.value().text);
-        }
-    }
-
-    void setExtraFormats(const QMap<int, QList<QTextLayout::FormatRange>> &formatMap)
-    {
-        QTC_ASSERT(m_highlighter, return);
-        for (auto it = formatMap.cbegin(); it != formatMap.cend(); ++it)
-            m_highlighter->setExtraFormats(m_document->findBlockByNumber(it.key()), it.value());
-    }
-
-    void clearExtraFormats(const QList<int> &blockNumbers)
-    {
-        QTC_ASSERT(m_highlighter, return);
-        for (auto it = blockNumbers.cbegin(); it != blockNumbers.cend(); ++it)
-            m_highlighter->clearExtraFormats(m_document->findBlockByNumber(*it));
-    }
-
-    void clearAllExtraFormats()
-    {
-        QTC_ASSERT(m_highlighter, return);
-        m_highlighter->clearAllExtraFormats();
-    }
-
-    void setFontSettings(const TextEditor::FontSettings &fontSettings)
-    {
-        QTC_ASSERT(m_highlighter, return);
-        m_highlighter->setFontSettings(fontSettings);
-    }
-
-    void setDefinitionName(const QString &name)
-    {
-        QTC_ASSERT(m_highlighter, return);
-        m_highlighter->setDefinitionName(name);
-    }
-
-    void setLanguageFeaturesFlags(unsigned int flags)
-    {
-        QTC_ASSERT(m_highlighter, return);
-        m_highlighter->setLanguageFeaturesFlags(flags);
-    }
-
-    void setEnabled(bool enabled)
-    {
-        QTC_ASSERT(m_highlighter, return);
-        m_highlighter->setEnabled(enabled);
-    }
-
-    void rehighlight()
-    {
-        QTC_ASSERT(m_highlighter, return);
-        m_highlighter->rehighlight();
-    }
-
-    void reformatBlocks(int from, int charsRemoved, int charsAdded)
-    {
-        QTC_ASSERT(m_highlighter, return);
-        m_highlighter->reformatBlocks(from, charsRemoved, charsAdded);
-    }
-
-    void setInterrupted(bool interrupted)
-    {
-        QTC_ASSERT(m_highlighter, return);
-        m_highlighter->setInterrupted(interrupted);
-    }
-
-    QPointer<SyntaxHighlighter> m_highlighter = nullptr;
-    QTextDocument *m_document = nullptr;
-
-signals:
-    void resultsReady(const QList<SyntaxHighlighter::Result> &result);
-
-};
-
-void SyntaxHighlighterRunner::HighlightingStatus::notInterrupted(int from,
-                                                                 int charsRemoved,
-                                                                 int charsAdded)
-{
-    m_from = from;
-    m_addedChars = charsAdded;
-    m_removedChars = charsRemoved;
-    m_current = from;
-    m_newFrom = from + m_addedChars;
-    m_interruptionRequested = false;
-}
-
-void SyntaxHighlighterRunner::HighlightingStatus::interrupted(int from,
-                                                              int charsRemoved,
-                                                              int charsAdded)
-{
-    m_newFrom = std::min(m_newFrom, from);
-    m_newFrom = std::min(m_current, m_newFrom);
-    m_removedChars += charsRemoved;
-    m_addedChars += charsAdded;
-    m_interruptionRequested = true;
-}
-
-void SyntaxHighlighterRunner::HighlightingStatus::applyNewFrom()
-{
-    m_from = m_newFrom;
-    m_current = m_newFrom;
-    m_interruptionRequested = false;
-}
-
-SyntaxHighlighterRunner::SyntaxHighlighterRunner(SyntaxHighlighter *highlighter,
-                                                 QTextDocument *document,
-                                                 bool async)
-    : d(new SyntaxHighlighterRunnerPrivate(highlighter, document, async))
-    , m_document(document)
-{
-    m_useGenericHighlighter = qobject_cast<Highlighter *>(d->m_highlighter);
-
-    if (async) {
-        m_thread.emplace();
-        d->moveToThread(&*m_thread);
-        connect(&*m_thread, &QThread::finished, d, &QObject::deleteLater);
-        m_thread->start();
-
-        connect(d,
-                &SyntaxHighlighterRunnerPrivate::resultsReady,
-                this,
-                &SyntaxHighlighterRunner::applyFormatRanges);
-
-        changeDocument(0, 0, m_document->characterCount());
-        connect(m_document,
-                &QTextDocument::contentsChange,
-                this,
-                &SyntaxHighlighterRunner::changeDocument);
-
-        m_foldValidator.setup(qobject_cast<TextDocumentLayout *>(document->documentLayout()));
-    } else {
-        connect(d,
-                &SyntaxHighlighterRunnerPrivate::resultsReady,
-                this,
-                [this](const QList<SyntaxHighlighter::Result> &result) {
-                    if (result.size() == 1
-                        && result.at(0).m_state == SyntaxHighlighter::State::Extras)
-                        return;
-
-                    auto done = std::find_if(result.cbegin(),
-                                             result.cend(),
-                                             [](const SyntaxHighlighter::Result &res) {
-                                                 return res.m_state
-                                                        == SyntaxHighlighter::State::Done;
-                                             });
-                    if (done != result.cend()) {
-                        m_syntaxInfoUpdated = SyntaxHighlighter::State::Done;
-                        emit highlightingFinished();
-                        return;
-                    }
-                    m_syntaxInfoUpdated = SyntaxHighlighter::State::InProgress;
-                });
-    }
-}
-
-SyntaxHighlighterRunner::~SyntaxHighlighterRunner()
-{
-    if (m_thread) {
-        m_thread->requestInterruption();
-        m_thread->quit();
-        m_thread->wait();
-    } else {
-        delete d;
-    }
-}
-
-void SyntaxHighlighterRunner::applyFormatRanges(const QList<SyntaxHighlighter::Result> &results)
-{
-    if (m_document == nullptr)
-        return;
-
-    if (m_highlightingStatus.m_interruptionRequested) {
-        d->setInterrupted(false);
-        m_highlightingStatus.applyNewFrom();
-        reformatBlocks(m_highlightingStatus.m_newFrom,
-                       m_highlightingStatus.m_removedChars,
-                       m_highlightingStatus.m_addedChars);
-        return;
-    }
-
-    auto processResult = [this](SyntaxHighlighter::Result result, QTextBlock docBlock) {
-        if (!docBlock.isValid())
-            return;
-
-        result.copyToBlock(docBlock);
-        m_highlightingStatus.m_current = docBlock.position() + docBlock.length() - 1;
-
-        if (result.m_formatRanges != docBlock.layout()->formats()) {
-            docBlock.layout()->setFormats(result.m_formatRanges);
-            m_document->markContentsDirty(docBlock.position(), docBlock.length());
-        }
-    };
-
-    if (results.size() == 1 && results.at(0).m_state == SyntaxHighlighter::State::Extras) {
-        QTextBlock docBlock = m_document->findBlockByNumber(results.at(0).m_blockNumber);
-        processResult(results.at(0), docBlock);
-        return;
-    }
-
-    for (const SyntaxHighlighter::Result &result : results) {
-        m_syntaxInfoUpdated = result.m_state;
-        if (m_syntaxInfoUpdated == SyntaxHighlighter::State::Start) {
-            m_foldValidator.reset();
-            continue;
-        }
-        if (m_syntaxInfoUpdated == SyntaxHighlighter::State::Done) {
-            m_foldValidator.finalize();
-            emit highlightingFinished();
-            return;
-        }
-
-        QTextBlock docBlock = m_document->findBlockByNumber(result.m_blockNumber);
-        processResult(result, docBlock);
-        m_foldValidator.process(docBlock);
-    }
-}
-
-void SyntaxHighlighterRunner::changeDocument(int from, int charsRemoved, int charsAdded)
-{
-    QTC_ASSERT(m_document, return);
-    SyntaxHighlighter::State prevSyntaxInfoUpdated = m_syntaxInfoUpdated;
-    m_syntaxInfoUpdated = SyntaxHighlighter::State::InProgress;
-
-    QMap<int, BlockPreeditData> blocksPreedit;
-    QTextBlock block = m_document->findBlock(from);
-    const QTextBlock endBlock = m_document->findBlock(from + charsAdded);
-    while (block.isValid() && block != endBlock) {
-        if (QTextLayout *layout = block.layout()) {
-            if (const int pos = layout->preeditAreaPosition(); pos != -1)
-                blocksPreedit[block.blockNumber()] = {pos, layout->preeditAreaText()};
-        }
-        block = block.next();
-    }
-    const QString text = Utils::Text::textAt(QTextCursor(m_document), from, charsAdded);
-    QMetaObject::invokeMethod(d, [this, from, charsRemoved, text, blocksPreedit] {
-        d->changeDocument(from, charsRemoved, text, blocksPreedit);
-    });
-
-    if (prevSyntaxInfoUpdated == SyntaxHighlighter::State::InProgress) {
-        m_highlightingStatus.interrupted(from, charsRemoved, charsAdded);
-        d->setInterrupted(true);
-    } else {
-        m_highlightingStatus.notInterrupted(from, charsRemoved, charsAdded);
-        d->setInterrupted(false);
-    }
-}
-
-bool SyntaxHighlighterRunner::useGenericHighlighter() const
-{
-    return m_useGenericHighlighter;
-}
-
-void SyntaxHighlighterRunner::setExtraFormats(
-    const QMap<int, QList<QTextLayout::FormatRange>> &formatMap)
-{
-    QMetaObject::invokeMethod(d, [this, formatMap] { d->setExtraFormats(formatMap); });
-}
-
-void SyntaxHighlighterRunner::clearExtraFormats(const QList<int> &blockNumbers)
-{
-    QMetaObject::invokeMethod(d, [this, blockNumbers] { d->clearExtraFormats(blockNumbers); });
-}
-
-void SyntaxHighlighterRunner::clearAllExtraFormats()
-{
-    QMetaObject::invokeMethod(d, [this] { d->clearAllExtraFormats(); });
-}
-
-void SyntaxHighlighterRunner::setFontSettings(const TextEditor::FontSettings &fontSettings)
-{
-    QMetaObject::invokeMethod(d, [this, fontSettings] { d->setFontSettings(fontSettings); });
-    rehighlight();
-}
-
-void SyntaxHighlighterRunner::setLanguageFeaturesFlags(unsigned int flags)
-{
-    QMetaObject::invokeMethod(d, [this, flags] { d->setLanguageFeaturesFlags(flags); });
-}
-
-void SyntaxHighlighterRunner::setEnabled(bool enabled)
-{
-    QMetaObject::invokeMethod(d, [this, enabled] { d->setEnabled(enabled); });
-}
-
-void SyntaxHighlighterRunner::rehighlight()
-{
-    if (m_syntaxInfoUpdated == SyntaxHighlighter::State::InProgress) {
-        m_highlightingStatus.interrupted(0, 0, m_document->characterCount());
-        d->setInterrupted(true);
-    } else {
-        m_highlightingStatus.notInterrupted(0, 0, m_document->characterCount());
-        d->setInterrupted(false);
-        QMetaObject::invokeMethod(d, [this] { d->rehighlight(); });
-    }
-}
-
-
-void SyntaxHighlighterRunner::reformatBlocks(int from, int charsRemoved, int charsAdded)
-{
-    QMetaObject::invokeMethod(
-        d,
-        [this, from, charsRemoved, charsAdded] {
-            d->reformatBlocks(from, charsRemoved, charsAdded);
-        });
-}
-
-QString SyntaxHighlighterRunner::definitionName()
-{
-    return m_definitionName;
-}
-
-void SyntaxHighlighterRunner::setDefinitionName(const QString &name)
-{
-    if (name.isEmpty())
-        return;
-
-    m_definitionName = name;
-    QMetaObject::invokeMethod(d, [this, name] { d->setDefinitionName(name); });
-}
-
-} // namespace TextEditor
-
-#include "syntaxhighlighterrunner.moc"
diff --git a/src/plugins/texteditor/syntaxhighlighterrunner.h b/src/plugins/texteditor/syntaxhighlighterrunner.h
deleted file mode 100644
index 16b7c1535c8..00000000000
--- a/src/plugins/texteditor/syntaxhighlighterrunner.h
+++ /dev/null
@@ -1,79 +0,0 @@
-// Copyright (C) 2023 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
-
-#pragma once
-
-#include <texteditor/fontsettings.h>
-#include <texteditor/syntaxhighlighter.h>
-#include <texteditor/texteditorsettings.h>
-
-#include <QObject>
-#include <QPointer>
-
-QT_BEGIN_NAMESPACE
-class QTextDocument;
-QT_END_NAMESPACE
-
-namespace TextEditor {
-
-class SyntaxHighlighterRunnerPrivate;
-
-class TEXTEDITOR_EXPORT SyntaxHighlighterRunner : public QObject
-{
-    Q_OBJECT
-public:
-    using SyntaxHighlighterCreator = std::function<SyntaxHighlighter *()>;
-
-    SyntaxHighlighterRunner(SyntaxHighlighter *highlighter, QTextDocument *document, bool async);
-    virtual ~SyntaxHighlighterRunner();
-
-    void setExtraFormats(const QMap<int, QList<QTextLayout::FormatRange>> &formats);
-    void clearExtraFormats(const QList<int> &blockNumbers);
-    void clearAllExtraFormats();
-    void setFontSettings(const TextEditor::FontSettings &fontSettings);
-    void setLanguageFeaturesFlags(unsigned int flags);
-    void setEnabled(bool enabled);
-    void rehighlight();
-    void reformatBlocks(int from, int charsRemoved, int charsAdded);
-
-    QString definitionName();
-    void setDefinitionName(const QString &name);
-
-    QTextDocument *document() const { return m_document; }
-    bool useGenericHighlighter() const;
-
-    bool syntaxInfoUpdated() const { return m_syntaxInfoUpdated == SyntaxHighlighter::State::Done; }
-
-signals:
-    void highlightingFinished();
-
-private:
-    void applyFormatRanges(const QList<SyntaxHighlighter::Result> &results);
-    void changeDocument(int from, int charsRemoved, int charsAdded);
-
-    SyntaxHighlighterRunnerPrivate *d;
-    QPointer<QTextDocument> m_document = nullptr;
-    SyntaxHighlighter::State m_syntaxInfoUpdated = SyntaxHighlighter::State::Done;
-
-    struct HighlightingStatus
-    {
-        int m_from = 0;
-        int m_addedChars = 0;
-        int m_current = 0;
-        int m_removedChars = 0;
-        int m_newFrom = 0;
-        bool m_interruptionRequested = false;
-
-        void notInterrupted(int from, int charsRemoved, int charsAdded);
-        void interrupted(int from, int charsRemoved, int charsAdded);
-        void applyNewFrom();
-    } m_highlightingStatus;
-
-    bool m_useGenericHighlighter = false;
-    QString m_definitionName;
-    std::optional<QThread> m_thread;
-    TextDocumentLayout::FoldValidator m_foldValidator;
-};
-
-} // namespace TextEditor
-
diff --git a/src/plugins/texteditor/textdocument.cpp b/src/plugins/texteditor/textdocument.cpp
index 2636ad46e23..9d8133912c8 100644
--- a/src/plugins/texteditor/textdocument.cpp
+++ b/src/plugins/texteditor/textdocument.cpp
@@ -10,10 +10,10 @@
 #include "tabsettings.h"
 #include "textdocumentlayout.h"
 #include "texteditor.h"
+#include "texteditorsettings.h"
 #include "texteditortr.h"
 #include "textindenter.h"
 #include "typingsettings.h"
-#include "syntaxhighlighterrunner.h"
 
 #include <coreplugin/coreconstants.h>
 #include <coreplugin/diffservice.h>
@@ -64,8 +64,6 @@ public:
 
     ~TextDocumentPrivate()
     {
-        if (m_highlighterRunner)
-            m_highlighterRunner->deleteLater();
     }
 
     MultiTextCursor indentOrUnindent(const MultiTextCursor &cursor, bool doIndent, const TabSettings &tabSettings);
@@ -101,7 +99,7 @@ public:
     TextMarks m_marksCache; // Marks not owned
     Utils::Guard m_modificationChangedGuard;
 
-    SyntaxHighlighterRunner *m_highlighterRunner = nullptr;
+    SyntaxHighlighter *m_highlighter = nullptr;
 };
 
 MultiTextCursor TextDocumentPrivate::indentOrUnindent(const MultiTextCursor &cursors,
@@ -462,8 +460,8 @@ void TextDocument::applyFontSettings()
         block = block.next();
     }
     updateLayout();
-    if (d->m_highlighterRunner)
-        d->m_highlighterRunner->setFontSettings(d->m_fontSettings);
+    if (d->m_highlighter)
+        d->m_highlighter->setFontSettings(d->m_fontSettings);
 }
 
 const FontSettings &TextDocument::fontSettings() const
@@ -533,6 +531,15 @@ bool TextDocument::applyChangeSet(const ChangeSet &changeSet)
 // the blocks list must be sorted
 void TextDocument::setIfdefedOutBlocks(const QList<BlockRange> &blocks)
 {
+    if (syntaxHighlighter() && !syntaxHighlighter()->syntaxHighlighterUpToDate()) {
+        connect(syntaxHighlighter(),
+                &SyntaxHighlighter::finished,
+                this,
+                [this, blocks] { setIfdefedOutBlocks(blocks); },
+                Qt::SingleShotConnection);
+        return;
+    }
+
     QTextDocument *doc = document();
     auto documentLayout = qobject_cast<TextDocumentLayout*>(doc->documentLayout());
     QTC_ASSERT(documentLayout, return);
@@ -635,11 +642,6 @@ QTextDocument *TextDocument::document() const
     return &d->m_document;
 }
 
-SyntaxHighlighterRunner *TextDocument::syntaxHighlighterRunner() const
-{
-    return d->m_highlighterRunner;
-}
-
 /*!
  * Saves the document to the file specified by \a fileName. If errors occur,
  * \a errorString contains their cause.
@@ -911,26 +913,19 @@ bool TextDocument::reload(QString *errorString, ReloadFlag flag, ChangeType type
     return reload(errorString);
 }
 
-void TextDocument::resetSyntaxHighlighter(const std::function<SyntaxHighlighter *()> &creator,
-                                          bool threaded)
+void TextDocument::resetSyntaxHighlighter(const std::function<SyntaxHighlighter *()> &creator)
 {
-    delete d->m_highlighterRunner;
-
-    static const std::optional<bool> envValue = []() -> std::optional<bool> {
-        const QString key("QTC_USE_THREADED_HIGHLIGHTER");
-        if (qtcEnvironmentVariableIsSet(key)) {
-            const QString value = qtcEnvironmentVariable(key).toUpper();
-            return value != "FALSE" && value != "0";
-        }
-        return {};
-    }();
-
     SyntaxHighlighter *highlighter = creator();
+    highlighter->setParent(this);
+    highlighter->setDocument(this->document());
     highlighter->setFontSettings(TextEditorSettings::fontSettings());
     highlighter->setMimeType(mimeType());
-    d->m_highlighterRunner = new SyntaxHighlighterRunner(highlighter,
-                                                         document(),
-                                                         envValue.value_or(threaded));
+    d->m_highlighter = highlighter;
+}
+
+SyntaxHighlighter *TextDocument::syntaxHighlighter() const
+{
+    return d->m_highlighter;
 }
 
 void TextDocument::cleanWhitespace(const QTextCursor &cursor)
diff --git a/src/plugins/texteditor/textdocument.h b/src/plugins/texteditor/textdocument.h
index 5879d9e9ec2..b3bf77e5442 100644
--- a/src/plugins/texteditor/textdocument.h
+++ b/src/plugins/texteditor/textdocument.h
@@ -34,7 +34,6 @@ class FontSettings;
 class IAssistProvider;
 class StorageSettings;
 class SyntaxHighlighter;
-class SyntaxHighlighterRunner;
 class TabSettings;
 class TextDocumentPrivate;
 class TextMark;
@@ -127,8 +126,8 @@ public:
     QTextDocument *document() const;
 
     using SyntaxHighLighterCreator = std::function<SyntaxHighlighter *()>;
-    void resetSyntaxHighlighter(const SyntaxHighLighterCreator &creator, bool threaded = false);
-    SyntaxHighlighterRunner *syntaxHighlighterRunner() const;
+    void resetSyntaxHighlighter(const SyntaxHighLighterCreator &creator);
+    SyntaxHighlighter *syntaxHighlighter() const;
 
     bool reload(QString *errorString, QTextCodec *codec);
     void cleanWhitespace(const QTextCursor &cursor);
diff --git a/src/plugins/texteditor/texteditor.cpp b/src/plugins/texteditor/texteditor.cpp
index 42daeeff6d3..85bd4732baa 100644
--- a/src/plugins/texteditor/texteditor.cpp
+++ b/src/plugins/texteditor/texteditor.cpp
@@ -34,7 +34,6 @@
 #include "texteditorsettings.h"
 #include "texteditortr.h"
 #include "typingsettings.h"
-#include "syntaxhighlighterrunner.h"
 
 #include <aggregation/aggregate.h>
 
@@ -1935,8 +1934,8 @@ void TextEditorWidgetPrivate::foldLicenseHeader()
             QStringList commentMarker;
             QStringList docMarker;
             HighlighterHelper::Definition def;
-            if (SyntaxHighlighterRunner *highlighter = q->textDocument()->syntaxHighlighterRunner())
-                def = HighlighterHelper::definitionForName(highlighter->definitionName());
+            if (auto highlighter = qobject_cast<Highlighter *>(q->textDocument()->syntaxHighlighter()))
+                def = highlighter->definition();
 
             if (def.isValid()) {
                 for (const QString &marker :
@@ -3494,10 +3493,10 @@ QByteArray TextEditorWidget::saveState() const
 
 bool TextEditorWidget::singleShotAfterHighlightingDone(std::function<void()> &&f)
 {
-    if (d->m_document->syntaxHighlighterRunner()
-        && !d->m_document->syntaxHighlighterRunner()->syntaxInfoUpdated()) {
-        connect(d->m_document->syntaxHighlighterRunner(),
-                &SyntaxHighlighterRunner::highlightingFinished,
+    if (d->m_document->syntaxHighlighter()
+        && !d->m_document->syntaxHighlighter()->syntaxHighlighterUpToDate()) {
+        connect(d->m_document->syntaxHighlighter(),
+                &SyntaxHighlighter::finished,
                 this,
                 [f = std::move(f)] { f(); }, Qt::SingleShotConnection);
         return true;
@@ -3741,10 +3740,11 @@ void TextEditorWidgetPrivate::configureGenericHighlighter(
 
     const QString definitionFilesPath
         = TextEditorSettings::highlighterSettings().definitionFilesPath().toString();
-    m_document->resetSyntaxHighlighter([definitionFilesPath] {
-        return new Highlighter(definitionFilesPath);
+    m_document->resetSyntaxHighlighter([definitionFilesPath, definition] {
+        auto highlighter = new Highlighter(definitionFilesPath);
+        highlighter->setDefinition(definition);
+        return highlighter;
     });
-    m_document->syntaxHighlighterRunner()->setDefinitionName(definition.name());
 
     m_document->setFontSettings(TextEditorSettings::fontSettings());
 }
@@ -3769,8 +3769,8 @@ void TextEditorWidgetPrivate::setupFromDefinition(const KSyntaxHighlighting::Def
 
 KSyntaxHighlighting::Definition TextEditorWidgetPrivate::currentDefinition()
 {
-    if (SyntaxHighlighterRunner *highlighter = m_document->syntaxHighlighterRunner())
-        return HighlighterHelper::definitionForName(highlighter->definitionName());
+    if (auto *highlighter = qobject_cast<Highlighter *>(m_document->syntaxHighlighter()))
+        return highlighter->definition();
     return {};
 }
 
@@ -5127,7 +5127,8 @@ void TextEditorWidgetPrivate::setupBlockLayout(const PaintEventData &data,
     blockData.layout = data.block.layout();
 
     QTextOption option = blockData.layout->textOption();
-    if (data.suppressSyntaxInIfdefedOutBlock && TextDocumentLayout::ifdefedOut(data.block)) {
+    if (data.suppressSyntaxInIfdefedOutBlock
+            && TextDocumentLayout::ifdefedOut(data.block)) {
         option.setFlags(option.flags() | QTextOption::SuppressColors);
         painter.setPen(data.ifdefedOutFormat.foreground().color());
     } else {
@@ -5746,8 +5747,8 @@ void TextEditorWidgetPrivate::paintCodeFolding(QPainter &painter,
     TextBlockUserData *nextBlockUserData = TextDocumentLayout::textUserData(nextBlock);
 
     bool drawBox = nextBlockUserData
-            && TextDocumentLayout::foldingIndent(data.block) < nextBlockUserData->foldingIndent();
-
+            && TextDocumentLayout::foldingIndent(data.block)
+            < nextBlockUserData->foldingIndent();
 
     const int blockNumber = data.block.blockNumber();
     bool active = blockNumber == extraAreaHighlightFoldBlockNumber;
@@ -8183,7 +8184,7 @@ void TextEditorWidget::setDisplaySettings(const DisplaySettings &ds)
     optionFlags.setFlag(QTextOption::AddSpaceForLineAndParagraphSeparators);
     optionFlags.setFlag(QTextOption::ShowTabsAndSpaces, ds.m_visualizeWhitespace);
     if (optionFlags != currentOptionFlags) {
-        if (SyntaxHighlighterRunner *highlighter = textDocument()->syntaxHighlighterRunner())
+        if (SyntaxHighlighter *highlighter = textDocument()->syntaxHighlighter())
             highlighter->rehighlight();
         QTextOption option = document()->defaultTextOption();
         option.setFlags(optionFlags);
diff --git a/src/plugins/texteditor/texteditor.qbs b/src/plugins/texteditor/texteditor.qbs
index 41fe08d51b5..30a4712b731 100644
--- a/src/plugins/texteditor/texteditor.qbs
+++ b/src/plugins/texteditor/texteditor.qbs
@@ -124,8 +124,6 @@ QtcPlugin {
         "storagesettings.h",
         "syntaxhighlighter.cpp",
         "syntaxhighlighter.h",
-        "syntaxhighlighterrunner.cpp",
-        "syntaxhighlighterrunner.h",
         "tabsettings.cpp",
         "tabsettings.h",
         "tabsettingswidget.cpp",
diff --git a/src/plugins/vcsbase/baseannotationhighlighter.cpp b/src/plugins/vcsbase/baseannotationhighlighter.cpp
index e3dce5ba266..0809d2c5237 100644
--- a/src/plugins/vcsbase/baseannotationhighlighter.cpp
+++ b/src/plugins/vcsbase/baseannotationhighlighter.cpp
@@ -4,6 +4,7 @@
 #include "baseannotationhighlighter.h"
 
 #include <texteditor/fontsettings.h>
+#include <texteditor/syntaxhighlighter.h>
 #include <texteditor/texteditorsettings.h>
 
 #include <utils/algorithm.h>
@@ -163,7 +164,7 @@ void BaseAnnotationHighlighter::rehighlight()
         return;
 
     setChangeNumbers(changes);
-    TextEditor::SyntaxHighlighter::rehighlight();
+    SyntaxHighlighter::rehighlight();
 }
 
 } // namespace VcsBase
diff --git a/src/plugins/vcsbase/vcsbaseeditor.cpp b/src/plugins/vcsbase/vcsbaseeditor.cpp
index 38bb004a2d6..13338584bf1 100644
--- a/src/plugins/vcsbase/vcsbaseeditor.cpp
+++ b/src/plugins/vcsbase/vcsbaseeditor.cpp
@@ -30,7 +30,7 @@
 #include <texteditor/texteditoractionhandler.h>
 #include <texteditor/textdocument.h>
 #include <texteditor/textdocumentlayout.h>
-#include <texteditor/syntaxhighlighterrunner.h>
+#include <texteditor/syntaxhighlighter.h>
 
 #include <utils/algorithm.h>
 #include <utils/progressindicator.h>
@@ -821,7 +821,7 @@ void VcsBaseEditorWidget::setFileLogAnnotateEnabled(bool e)
 
 void VcsBaseEditorWidget::setHighlightingEnabled(bool e)
 {
-    textDocument()->syntaxHighlighterRunner()->setEnabled(e);
+    textDocument()->syntaxHighlighter()->setEnabled(e);
 }
 
 FilePath VcsBaseEditorWidget::workingDirectory() const
@@ -1102,7 +1102,7 @@ void VcsBaseEditorWidget::slotActivateAnnotation()
 
     disconnect(this, &QPlainTextEdit::textChanged, this, &VcsBaseEditorWidget::slotActivateAnnotation);
 
-    if (SyntaxHighlighterRunner *ah = textDocument()->syntaxHighlighterRunner()) {
+    if (SyntaxHighlighter *ah = textDocument()->syntaxHighlighter()) {
         ah->rehighlight();
     } else {
         BaseAnnotationHighlighterCreator creator = annotationHighlighterCreator();
diff --git a/tests/auto/texteditor/highlighter/tst_highlighter.cpp b/tests/auto/texteditor/highlighter/tst_highlighter.cpp
index 9044065a019..e0806382982 100644
--- a/tests/auto/texteditor/highlighter/tst_highlighter.cpp
+++ b/tests/auto/texteditor/highlighter/tst_highlighter.cpp
@@ -7,7 +7,6 @@
 
 #include <texteditor/semantichighlighter.h>
 #include <texteditor/syntaxhighlighter.h>
-#include <texteditor/syntaxhighlighterrunner.h>
 #include <texteditor/texteditorsettings.h>
 
 #include <QObject>
@@ -32,7 +31,7 @@ private slots:
 
 private:
     QTextDocument *doc = nullptr;
-    SyntaxHighlighterRunner *highlighterRunner = nullptr;
+    SyntaxHighlighter *highlighter = nullptr;
     FontSettings fontsettings;
     QHash<int, QTextCharFormat> formatHash;
     QTextCharFormat whitespaceFormat;
@@ -58,8 +57,7 @@ Last)";
 
     doc = new QTextDocument();
     doc->setPlainText(text);
-    auto highlighter = new SyntaxHighlighter(doc, fontsettings);
-    highlighterRunner = new SyntaxHighlighterRunner(highlighter, doc, false);
+    highlighter = new SyntaxHighlighter(doc, fontsettings);
 }
 
 static const HighlightingResults &highlightingResults()
@@ -77,7 +75,7 @@ void tst_highlighter::test_setExtraAdditionalFormats()
 {
     QCOMPARE(doc->blockCount(), 4);
 
-    SemanticHighlighter::setExtraAdditionalFormats(highlighterRunner, highlightingResults(), formatHash);
+    SemanticHighlighter::setExtraAdditionalFormats(highlighter, highlightingResults(), formatHash);
 
     for (auto block = doc->firstBlock(); block.isValid(); block = block.next()) {
         QVERIFY(block.blockNumber() < 4);
@@ -140,17 +138,17 @@ void tst_highlighter::test_clearExtraFormats()
 {
     QCOMPARE(doc->blockCount(), 4);
 
-    SemanticHighlighter::setExtraAdditionalFormats(highlighterRunner, highlightingResults(), formatHash);
+    SemanticHighlighter::setExtraAdditionalFormats(highlighter, highlightingResults(), formatHash);
 
     QTextBlock firstBlock = doc->findBlockByNumber(0);
     QTextBlock spacesLineBlock = doc->findBlockByNumber(1);
     QTextBlock emptyLineBlock = doc->findBlockByNumber(2);
     QTextBlock lastBlock = doc->findBlockByNumber(3);
 
-    highlighterRunner->clearExtraFormats({emptyLineBlock.blockNumber()});
+    highlighter->clearExtraFormats(emptyLineBlock);
     QVERIFY(emptyLineBlock.layout()->formats().isEmpty());
 
-    highlighterRunner->clearExtraFormats({spacesLineBlock.blockNumber()});
+    highlighter->clearExtraFormats(spacesLineBlock);
 
     auto formats = spacesLineBlock.layout()->formats();
     // the spaces are not extra formats and should remain when clearing extra formats
@@ -185,7 +183,7 @@ void tst_highlighter::test_clearExtraFormats()
     QCOMPARE(formats.at(1).start, 0);
     QCOMPARE(formats.at(1).length, 5);
 
-    highlighterRunner->clearAllExtraFormats();
+    highlighter->clearAllExtraFormats();
 
     QVERIFY(firstBlock.layout()->formats().isEmpty());
     QVERIFY(emptyLineBlock.layout()->formats().isEmpty());
@@ -221,7 +219,7 @@ void tst_highlighter::test_incrementalApplyAdditionalFormats()
 
     QFutureInterface<HighlightingResult> fiOld;
     fiOld.reportResults(highlightingResults());
-    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighterRunner,
+    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighter,
                                                                 fiOld.future(),
                                                                 2,
                                                                 0,
@@ -229,7 +227,7 @@ void tst_highlighter::test_incrementalApplyAdditionalFormats()
     auto formats = firstBlock.layout()->formats();
     QVERIFY(formats.isEmpty());
 
-    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighterRunner,
+    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighter,
                                                                 fiOld.future(),
                                                                 0,
                                                                 2,
@@ -254,7 +252,7 @@ void tst_highlighter::test_incrementalApplyAdditionalFormats()
     QCOMPARE(formats.at(1).start, 11);
     QCOMPARE(formats.at(1).length, 1);
 
-    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighterRunner,
+    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighter,
                                                                 fiOld.future(),
                                                                 3,
                                                                 6,
@@ -280,7 +278,7 @@ void tst_highlighter::test_incrementalApplyAdditionalFormats()
 
     QFutureInterface<HighlightingResult> fiNew;
     fiNew.reportResults(newResults);
-    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighterRunner,
+    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighter,
                                                                 fiNew.future(),
                                                                 0,
                                                                 3,
@@ -294,7 +292,7 @@ void tst_highlighter::test_incrementalApplyAdditionalFormats()
     QCOMPARE(formats.at(0).start, 0);
     QCOMPARE(formats.at(0).length, 1);
 
-    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighterRunner,
+    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighter,
                                                                 fiNew.future(),
                                                                 3,
                                                                 4,
@@ -305,14 +303,14 @@ void tst_highlighter::test_incrementalApplyAdditionalFormats()
     QVERIFY(formats.isEmpty());
 
     // QTCREATORBUG-29218
-    highlighterRunner->clearAllExtraFormats();
+    highlighter->clearAllExtraFormats();
     const HighlightingResults bug29218Results{HighlightingResult(1, 1, 2, 0),
                                               HighlightingResult(1, 3, 2, 1)};
     QFutureInterface<HighlightingResult> fi29218;
     fi29218.reportResults(bug29218Results);
     formats = firstBlock.layout()->formats();
     QVERIFY(formats.isEmpty());
-    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighterRunner,
+    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighter,
                                                                 fi29218.future(),
                                                                 0,
                                                                 1,
@@ -323,7 +321,7 @@ void tst_highlighter::test_incrementalApplyAdditionalFormats()
     QCOMPARE(formats.at(0).format.fontOverline(), false);
     QCOMPARE(formats.at(0).start, 0);
     QCOMPARE(formats.at(0).length, 2);
-    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighterRunner,
+    SemanticHighlighter::incrementalApplyExtraAdditionalFormats(highlighter,
                                                                 fi29218.future(),
                                                                 1,
                                                                 2,
@@ -347,7 +345,7 @@ void tst_highlighter::test_preeditText()
     QTextBlock firstBlock = doc->findBlockByNumber(0);
     firstBlock.layout()->setPreeditArea(2, "uaf");
 
-    SemanticHighlighter::setExtraAdditionalFormats(highlighterRunner, highlightingResults(), formatHash);
+    SemanticHighlighter::setExtraAdditionalFormats(highlighter, highlightingResults(), formatHash);
 
     auto formats = firstBlock.layout()->formats();
     QCOMPARE(formats.size(), 2);
@@ -366,7 +364,7 @@ void tst_highlighter::cleanup()
 {
     delete doc;
     doc = nullptr;
-    highlighterRunner = nullptr;
+    highlighter = nullptr;
 }
 
 } // namespace TextEditor