Mouse Lag

[Windmill]

Hey, I recently bought Amnesia and am experiencing some bad mouse lag. It's really odd, I noticed the mouse cursor in the main menu not having a smooth, sliding animation, if you will, but I thought it was just a small developmental oversight. Note, at this time, the flame in the main menu is flickering smoothly. So, I start a game, and the opening cutscene of the player fading in and out of stream of consciousness occurs smoothly, but when I noticed that you can look around during these scenes, I found the movement of my camera to be very rough and lack fluidity that you would normally find in just browsing your desktop.

Specs:
Processor: i7 965 OC'd to 4.0ghz
GPU (x2): SLi GTX 280
RAM: 6GB
Mouse: Logitech G5

Any help would be appreciated, because this mouse lag makes the game unplayable.

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Okay, Update:
I just turned everything to the lowest setting and the mouse lag seems to have gone away.. but, I really dont understand what can be taxing my system. Sampling?

[avager]

Check what FPSs do you have ingame by using any 3rd party program (fraps or whatever).

I had some weird problems on my:

Intel core duo e8400 (3,0 ghz)
GTX 260
2 GB ram

where with NONE changes in my settings, FPS dropped down to 20 or 15... sometimes even to 1 frame per 5 seconds... after playing around in settings, I changed something from Hight to Medium then back to High, I received boost to 200 fps (turned off limit in config file).
First time, game looked pretty smooth, but mouse didn't (~25 fps). Right now, with 90-120 FPS I can finally play it how I should do it in first place :S .

Hint:
Play around SSAO, Parallax and Shadow resolutions (turn them off and turn them back on...mostly works with Parallax and shadow resolution set to medium and back to high :O ). Maybe they lag your controls somehow.

Check for vsync if it's being turned off (force it off in nvidia's control panel).
Unlock more FPS in config ini located in "Documents" folder of your system... maybe this will help.