diff -rupN Python-2.7.13/Lib/distutils/cygwinccompiler.py Python-2.7.13-new/Lib/distutils/cygwinccompiler.py
--- Python-2.7.13/Lib/distutils/cygwinccompiler.py	2017-01-21 01:46:11.463554632 +0100
+++ Python-2.7.13-new/Lib/distutils/cygwinccompiler.py	2017-01-21 01:46:14.179525634 +0100
@@ -330,9 +330,9 @@ class Mingw32CCompiler (CygwinCCompiler)
         else:
             no_cygwin = ''
 
-        self.set_executables(compiler='gcc%s -O -Wall' % no_cygwin,
-                             compiler_so='gcc%s -mdll -O -Wall' % no_cygwin,
-                             compiler_cxx='g++%s -O -Wall' % no_cygwin,
+        self.set_executables(compiler='gcc%s -O2 -Wall' % no_cygwin,
+                             compiler_so='gcc%s -mdll -O2 -Wall' % no_cygwin,
+                             compiler_cxx='g++%s -O2 -Wall' % no_cygwin,
                              linker_exe='gcc%s' % no_cygwin,
                              linker_so='%s%s %s %s'
                                     % (self.linker_dll, no_cygwin,