--- Qt/Settings.pri.orig	2016-01-04 21:37:36.600078151 +0800
+++ Qt/Settings.pri	2016-01-04 21:37:57.430078511 +0800
@@ -64,7 +64,7 @@
 	else: QMAKE_CXXFLAGS += -std=c++11
 	QMAKE_CFLAGS_RELEASE ~= s/-O.*/
 	QMAKE_CXXFLAGS_RELEASE ~= s/-O.*/
-	QMAKE_ALLFLAGS_RELEASE += -O3 -ffast-math
+	QMAKE_ALLFLAGS_RELEASE += -O2 -ffast-math
 }
 
 contains(QT_CONFIG, opengles.) {