The Oblivion tweak guide from Tweakgudies.com is finally out. Mr. Ghazi has been hard at work, trying out just about every option in the ini file, and has delivered a very comprehensive guide on how to tweak it. There's no miracle tweak to dramatically boost performance without reducing image quality, but you'll find some decent ones that will boost performance and still leave the game looking beautiful.
"However, by the same token given how beautiful and complex Oblivion is, it is only natural that it be a very demanding game on most systems. There are a wide range of people experiencing performance issues, and there's been a mad scramble by players to find any and every means of increasing their framerates and resolving crashes. Fortunately, we have also seen some great efforts by the community as a whole to rapidly come up with tips and tweaks for Oblivion. This guide has been compiled to draw together all the working tips and tweaks, describe all the in-game settings in detail, provide all the useful console commands and give a range of troubleshooting and general performance advice in an effort to provide a single easy-to-use accurate reference source for Oblivion tweaking."