Like several others, I'm affected by a particularly infuriating bug that causes FPS to plummet like a turd the second a moving rope is shown on-screen. This is particularly egregious in the opening level, and - from what I hear - in a museum level that takes place later in the game. That's not to say it doesn't cause some form of trouble in several other levels as well, of course.

A quick way to see if you have the problem goes like this:

In the opening level, one of the first things you do is scale a long staircase leading to a small control room. Psycho tells you to use the silencer on your pistol, and you enter a room with a solitary enemy with his back to you, operating some generic, nondescript sci-fi computer. The game wants you to Stealth-Kill him. That done, look out the small window directly in front of you, leading out to a small cargo-hold. The FPS will drop like a brick. As long as you look anywhere else, it ought to be fine. But God forbid you look out that window into that tiny, little room with five people in it!

If you look a little closer, you'll see a crane with a large, heavy-looking crate of some description suspended from ropes, moving slowly from one end of the room to the other. Eventually, it will stop and the crate will slowly stop swinging. Once it's completely motionless, you'll notice the FPS suddenly rockets back up to normal.

I chose this example because it's the most overt situation in which you can see this truly ludicrously dumb bug in all its majesty; but this is only one case out of several. There are situations where you see an area laid out in front of you where the FPS is just awful, until you move your camera three centimeters down so that a lone swinging rope at the top-right of the screen is no longer visible, and the FPS suddenly shoots back up. It's just **** silly, there's no other word for it.

This takes place in other levels as well - it seems it's not just the ropes that have this issue.

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My specs, in case you'd find it informative:


"Two 'NVIDIA GeForce GTX 680's in SLI. (Latest drivers.)
16GB RAM.
'Intel Core i7-3960X'.
64-BIT 'Windows 7 Ultimate'.
'Creative SB X-FI Titanium'. (Latest drivers.)

Game runs from a fast SSD-harddrive."

I run the game at "Ultra"-settings, with everything maxed-out, save for "VSync", which is disabled. The game mostly runs okay, except for when the aforementioned ropes and such are shown.

I do not have this problem The only level in the game I get a really bad slowdown in is welcome to the jungle. I usually run the game on high with high textures at about 45+ fps until I walk out into all that tall grass and then I get 30 and below. It's only bad in that chapter. I run smooth everywhere else.. I have a q6600 @ 3.9 ghz and a stock gtx 560 ti. I have tried what you said with no issues.