Make sure the "Windowed" option is unchecked. This is checked by default even though the game also starts in full screen by default. As far as I can tell, the only thing checking this box does is make vsync not work.* Sometimes the Vsync does not get enabled even though it is set to on in the settings menu. The 3 times I loaded the game on 2 of them the vsync did not kick in, on the 3rd one it did.