I can't seem to get this game to run smoothly. It runs well enough when Garrett is in the dark, but if there's light or shadows involved, it starts to slow down. Also, I sometimes can't start the lockpicking minigame. The view starts to change, freezes, then goes back to normal. Here are the things I've tried to fix it:

1) Set it to run as Admin
2) Toggling bloom and vsync
3) Editing default.ini to be sure vsync was on/off
4) Editing default.ini to increase the cache size (up to 1024)
5) Set my affinity manually via a batch file.

I think that's everything, but nothing has had an effect. And my specs are:

Windows 7 64bit
Core2Duo T8300 2.4GHz
4GB RAM
NVidia GForce 8400M GS

What else can I do? Thanks.

Try the Sneaky Upgrade; this fixes multi-core issues and various other things. That would help narrow down what's wrong.

Thanks for the suggestion, and keep 'em coming. I gave it a shot, but I don't see a difference.

I am having the same problem. I can't lock pick at all. The animations just lock up. I've forced vsync every way I can on every file I can. I've checked to make sure my monitor refresh is at 60hz. I've installed tweaks and texture and I've even tried manually adjusting the animation speeds. Still can't lockpick. Any other advice would be much appreciated.

I too am suffering from severe framerate drops in particular areas. Not necessarily always well-lit areas, though it originally seemed that way. Most of the time the game runs fine even in the most detailed rooms but occasionally (particularly in newly-loaded areas) the framerate drops to unplayable levels. I've done my best to ignore it so far but it's crippled the haunted ship mission as the corridor through the center of the ship seems to have been hit with this shit fps curse.

It may be interesting to note that sometimes these areas miraculously spring back to decent speeds when I do a switch to the third person camera and swivel the camera around a bit, but this only works sometimes (like in Garret's house). I have no idea why this would do anything to help performance. It's pretty weird.

I've discovered a way out of the locpicking problem, but its a bit of mess around. Knowing that the issue is to do with the game's fps being too high, I downloaded a third party piece of software that would cap the fps for 3d applications. I used dxtory but there are others that can do it. I capped the game at 60 fps and voila. I can now lockpick and play the game. Not sure how to fix the slow down other users are having though.

Thanks!
This worked for me! I'm using MSI Afterburner, it works the same.