I have found that going back to the 190.62 Nvidia Drivers doesn't help that much. On my Nvidia 8800 GTS 640MB the two settings that need to change for a smooth frame rate are:
Shadows: Low Even medium creates stuttering.
Screen space ambient occlusion: Off (It cut my FPS in half with it on.)
With those two settings changed I can have all other settings up on high... including 8x AA. With these two settings unchanged, changing every other setting in the game did not help me enough to make it playable.
Also, turning off post-processing should give you a few FPS, but not enough to outweigh the benefits of the above items. You shouldn't have to turn this off but is you need just another couple FPS, this will do it.