I am one of the many that are having the horrible framerate problems. Several days ago I disabled all Autosave options and that seemed to have helped some. Last night when doing the "Hitting the Books" quest I was going up a set of stairs right before you go in the room and confront The Caller. At the top of the steps the game completely froze for 6-7 seconds and next thing I know it says "Autosaving..." in the upper left?? Obviously, I have several questions here:
A.) Why is it Autosaving when all the options have been disabled?
B.) Why would it Autosave at the top of a stairway? I wasn't going through a door or anything?

After killing The Caller and getting my 3 books I manually saved the game and shut it down and went to the XMB. Sure enough, 1 Autosave file was sitting there with the picture of my character at the top of the steps.

That happend to me aswell.