After I modified int CCApplication::run() function in cocos2dx/platform/win32/CCApplication_win32.cpp
sleep(0) to sleep(17) in the while(1) loop, CPU usage can go below 50 on my laptop (or 100 per CPU accordingly).
(sleep(17) means sleep for about 1/60s = 16.67 msecs.)
To test the lowered CPU usage you should call
CCDirector::sharedDirector()->setAnimationInterval(1.0 / 10); or