V-Sync clamps your FPS, so that's one thing.
That said, I have a GTX 580 with an i7-2600k and it runs butter smooth now. At first the game stuttered when panning, but now there are no noticeable problems.

I disabled texture streaming, but I don't think that affects your problem.

Is it noticeable though? Is stuff stuttering or slowing down? Is it being lagged by your recording software?