I am running on 8800 GTX, E6600 (overclocked at 3GHZ), 4GB ram and 74GB VelociRaptor and I'm barely getting 25-30 on low settings... Your not the only one, hopefully they will patch up the performance somehow.
Why do people keep saying this? It's not the design, its a nasty bug which I am sure will get addressed; hopefully sooner then later because I'm not buying the game until it does.
To all those people who believe that this mouse lag is to simulate the weight of the weapon I ask you this: why does it lag when you don't have a weapon?? Why does it lag in vehicles.
Example 1: boot camp, you start out without a weapon and there is mouse lag...
Example 2: Equip a pistol or better yet no weapon at all and there is still lag...
I rest my case.
Will try out the suggestions right now.. hope it works.
EDIT:
Nope, Enhanced Mouse Pointer and Triple Buffering are off and I'm still getting mouse lag :-( This sucks.
They need to fix the freaking mouse lag... This is the worst bug for ANY FPS game; bet they lost tens of thousands of dollars who dl the demo and decided not to buy the game cuz of the mouse lag. Personally I am waiting to see when it gets fixed; love the demo but not paying or playing a full game like this.