-webkit-transform: translate3d(0,0,0); makes some devices run their hardware acceleration.
A good read is found Here
Native applications can access the device’s graphical processing unit (GPU) to make pixels fly. Web applications, on the other hand, run in the context of the browser, which lets the software do most (if not all) of the rendering, resulting in less horsepower for transitions. But the Web has been catching up, and most browser vendors now provide graphical hardware acceleration by means of particular CSS rules.
-webkit-transform: translate3d(0,0,0); will kick the GPU into action for the CSS transitions, making them smoother (higher FPS).
translate3d(0,0,0) does nothing in terms of what you see. it moves the object by 0px in x, y and z axis. It's only a technique to force the hardware acceleration.
An alternative is
-webkit-transform: translateZ(0). And If there's flickering on Chrome and Safari due to transforms, try
-webkit-backface-visibility: hidden and
-webkit-perspective: 1000. For more info refer to this article.