Open-source Radeon users (Linux)
The Open-Source Radeon driver enforces Vsync by default. On at least Radeon 6790 cards the framerate is better (constant 60FPS without tearing) with it turned off.
From the Arch Linux wiki page on radeon:
The radeon driver will enable vsync by default, which is perfectly fine except for benchmarking. To turn it off, create ~/.drirc (or edit it if it already exists) and add the following section:
<driconf> <device screen="0" driver="dri2"> <application name="Default"> <option name="vblank_mode" value="0" /> </application> </device> </driconf>
After editing/creating this file, restart X to complete the changes. For most users this involves logging out and back in again.