To cut straight to the point: There is a problem with Skyrim's built in AA/Anisropic Filtering which can result in far lower than expected framerates and poor/no animation on foliage.

This is resolved by disabling these options in the game's configuration settings and instead using your graphics card's driver settings to achieve these effects.

I am running an i7 920 CPU at default speeds and two Nvidia GTX 285's in SLI at default speeds and am able to run Skyrim at 1920x1200 resolution on Ultra settings with everything maxed out and 8X AA and 16X AF with additional ini. file tweaks further enhancing the graphics and the game runs smooth as butter with high framerates at all times, no lag or stuttering ever.

Go to Skyrim's launcher => options and disable Anti Aliasing and Anosropic Filtering.

Then go to your video card's configuration settings and force AA and Anisropic Filtering there instead.

Initially I was using the built in settings in the game, with my video card drivers set to use the in-game settings and was getting framerate drops, stuttering and unbeknown to me, foliage was barely animating. Making these simple adjustments fixed all of it and has made the game immensely more enjoyable.

Sounds just like oblivion.. kinda. I know a few people preferred to use AA through their graphic card software, because AA in that game wasn't exactly AA.

I get good (for me) frame rates in 1080p on the GTS 450 with 2x for both of these. It recommended like 4 or 8 but I turned that down right away, since that's a pointless waste of resources.

I'm sure for the extremely picky people, occasional rare frame drops would be intolerable, but for me the game running smoothly 90% of the time is good enough. I'd recommend trying 2x before turning it off entirely.

Thanks. Any more tips?
Mine should run smoothly, but got bad performance at high.

Are there any way to disable shadows? They look crappy.

Nice. Thanks for this. I wasn't really getting bad performance, but my trees and stuff definitely weren't animating before now that I have this in comparison.

Very nice info.

I actually tried this (6950 here) and got horrible results. Had to revert back to in game use because framerate took an unplayable dive.

I didn't really have a reason to try it, other than people said the game's weren't working well, but just thought I'd see how it went.

My performance before trying it was totally fine, so not sure what was going on, other than that my card is amd and people have said the game hasn't been optimized for them yet.

I'd like to know this too. I agree.

Plus it'll help with the framerates.
But ate there any other tips to increase the performance while still staying at high?

I got an AMD Radeon HD 6850, 8GB of RAM and a 3,4GHz Quad Core processor.

I got mixed results with this. i7 720, ATI Mobility HD 5870, 6GB RAM.

Framerate seemed to be about the same.

Had the same result when I tested with my 6970, but I did a bit more experimentation and found that turning off the AA and AF in game, and setting Catalyst AA to 8x with Enhanced Application Setting and Edge Detect filter and AF to 16x gives me the best performance, and I actually do get the animated trees and foliage now.

I'll try it later. Thanks for the tip. Though my fps is ok. 60 in less-crowded areas. 30 in the middle of the first village that you go to.