diff --git a/platformio/platforms/base.py b/platformio/platforms/base.py
index e1bcc20f..d91118ec 100644
--- a/platformio/platforms/base.py
+++ b/platformio/platforms/base.py
@@ -132,6 +132,7 @@ class PlatformFactory(object):
         return module
 
     @classmethod
+    @util.memoized
     def _lookup_platforms(cls):
         platforms = {}
         for d in (util.get_home_dir(), util.get_source_dir()):