On macOS and Linux, I haven't noticed any performance issues with Emacs. On Windows, however, the performance is significantly worse. To make matters worse, I even have to patch w32.c just to get it to build:

@@ -10298,7 +10298,7 @@ w32_read_registry (HKEY rootkey, Lisp_Object lkey, Lisp_Object lname) /* mingw.org's MinGW doesn't declare _dstbias. MinGW64 defines it as a macro. / #ifndef _dstbias -__MINGW_IMPORT int _dstbias; +__MINGW_IMPORT long _dstbias; #endif

/ Fix a bug in MS implementation of 'tzset'. This function should be