Very strange phenomenon in QML animation with openGL

[aabc]

I have a QDeclarativeView running a Qml application which performing animation (Property animation). My QApplication using openGL as the graphics system.
When my display refresh rate is 60Hz the CPU consumption is about 65% but when i change
the display refresh rate to 75Hz the CPU consumption went down to about 5%.

Does anyone know the reason for that ?

[frankcyblogic.de]

Just a note: The animation timer inside the Animation framework is limited to 60 Hz. Just checked it some days ago on Qt 4.7 . Therefore you won't get more frames, but just more property updates. It's difficult to tell what your problem is about, without knowing the code.