I started getting lots of frame rate issues around the 6mb mark if I recall correctly. So I made a new character (then several others *rolls eyes*) and disabled all the auto-save stuff. Rarely fast travel or wait (though I sleep a lot). Granted the fast travel/wait was for RP reasons, but on the odd occasion where I did wait a lot to level smithing for example, the frame rate got really bad again.
So only manual saving and minimal use of fast traveling and waiting have helped my frame rate issues a lot. The patch further helped but the game isn't as pretty now, less atmospheric affects like fog and so on, but ohwells. :b