Compile-time performance of printing a prefix improved

src/include/units/format.h

@@ -47,18 +47,19 @@ namespace units {
     void print_prefix_or_ratio(std::basic_ostream<CharT, Traits>& os)
     {
       if constexpr(Ratio::num != 1 || Ratio::den != 1) {
+        if(!std::same_as<PrefixType, no_prefix>) {
           using prefix = downcast_target<detail::prefix_base<PrefixType, Ratio>>;
 
           if constexpr(!std::same_as<prefix, prefix_base<PrefixType, Ratio>>) {
             // print as a prefixed unit
             os << prefix::symbol;
+            return;
+          }
         }
-        else {
         // print as a ratio of the coherent unit
         print_ratio<Ratio>(os);
       }
     }
-    }
 
     template<typename CharT, typename Traits, typename... Es>
     void print_dimensions(std::basic_ostream<CharT, Traits>& os, dimension<Es...>)