Use optimization level -O2

builder.py

@@ -62,7 +62,7 @@ class error(Exception):
         return self.msg
 
 def common_flags():
-    return ['-O',
+    return ['-O2',
             '-g',
             '-fno-strict-aliasing',
             '-ffreestanding',

wscript

@@ -58,7 +58,7 @@ def build(bld):
 
     # C/C++ flags
     common_flags = []
-    common_flags += ["-O"]
+    common_flags += ["-O2"]
     common_flags += ["-g"]
     common_flags += ["-fno-strict-aliasing"]
     common_flags += ["-ffreestanding"]