Cocos2dx-win8 performance issue

Hi, I add a picture to “HelloWorld” project in the cocos2dx-win8 platform,but picture size is 1024x768.
And the fps from 60 to 45.
How do I improve performance?
Or I made a mistake to use?

I download cocos2dx-win8 code in the https://github.com/cocos2d-x/cocos2dx-win8.