My autoexec.cfg is only
r_TexturesStreamPoolSize = 1024
i_mouse_accel 0
i_mouse_smooth 0
i_mouse_accel_max 0
sys_MaxFps=120 (also in sys.cfg)

All my in-game settings are at medium except texture resolution (very high).
Vsync off.
AA is disabled, and I'm using SweetFx Smaa injector. Game is gorgeous. Looks like I'm running it on very High.

I have a GTX 580, I overclocked it a bit and raised the voltage too. These cards lack juice to begin with. 3GB version.

PLayed 5 hours straight SIngle player not a hitch 50/100 fps (Low/High)

314.07 drivers.