EDIT: FIXED! Fix found here: http://forums.nexusmods.com/index.php?/topic/971104-fps-drop-to-1-2-during-battle-for-whiterun-plz-help/

Now I'm getting about 2 fps.

After about 100 hours with a ton of mods, and not too much trouble anywhere else. Of course I assumed it must be a mod problem so I uninstalled all of them. Still wasnt any better, so I uninstalled and reinstalled skyrim, created a new game with just the official plug-ins. No improvement.

Everywhere else is fine, but as soon as I get to the catapults, the game becomes unplayable.

I've also tried using unofficial patches and fps boosters like Hidalgo. No effect. I've tried running in windowed mode. Setting all graphic options to minimum. Nothing helps.

Any other ideas? I Reeeealy want to play the civil war questline!

System specs:

AMD phenom 8400 triple core 2.10 ghz

GeForce gtx 260

windows 7 pro 64-bit

8 gb ram

Thanks!

My suggestion would be to try and go for a more dry run. Turn off every mod you have, just for one unsaved go at it. If that works, pick every mod that is absolutely vital to your survival (like, custom armor) or things you simply do not want to spend time getting back - include those in your second dry run. Once you make it past the area, it should be safe to engage them again. Alternately, you could try disabling mods one by one down a list, keeping those disabled still disabled, and seeing if one, two, or more of those is messing up the game.

Alternatively, I don't know if this is an option you want to explore, but you could always just mod out all the catapults.

And for what it's worth, I started the Civil War at hour 400. It's really nothing special...

Thanks for the reply.

As I said, This occurs even with no mods active at all.

I've also followed the S.T.E.P. guide and installed skyrim to a separate hard drive. still no luck.

Fixed it! Thank you random internet user!!

http://forums.nexusmods.com/index.php?/topic/971104-fps-drop-to-1-2-during-battle-for-whiterun-plz-help/