I used to get great performance on ultra-high settings, but now it was terrible. I actually had better performance back when I had a 8800 GT.
Someone recommended downgrading my video drivers to something older, so I installed 275.33 from June 2011, and it runs quite noticeably ALOT better.
Unfortunately this is going to cause problems with pretty much any other game I play, is there a fix to get Oblivion running properly with modern drivers?