--- a/buildtools/config.py
+++ b/buildtools/config.py
@@ -229,9 +229,6 @@ class Configuration(object):
                 for lst in [self.cflags, self.cxxflags]:
                     lst.append('-ggdb')
                     lst.append('-O0')
-            else:
-                for lst in [self.cflags, self.cxxflags]:
-                    lst.append('-O3')
 
             lflags = self.getWxConfigValue('--libs')
             self.MONOLITHIC = (lflags.find("_xrc") == -1)