I am currently trying to evaluate the performance of WebKit's CSS animations on various platforms. I've not been able to find a way to instrument a build of WebKit that will measure the frames-per-second rendered while performing an animation. Does anyone know how this can be done?
I decided to ask this same question on the WebKit dev list and got a decent response. I'll re-iterate that here.
Basically CSS animations in WebKit could be either rendered using one of 2 paths. The software rendering path, or the hardware path. In the case of the software path, the render loop is based on a timer and as such using a timer and counting how quickly the timer can fire will give an approximate FPS measurement. In the case of the hardware path the hardware will determine the path and there is no way to gather this information currently.
I'm rephrasing the response I got a bit, but this is the thrust of it I believe.
来源：https://stackoverflow.com/questions/5113245/instrument-webkit-to-provide-fps-information-for-css-animations