Also, Morrowind tended to keep track of not only a corpse location, but individual items and door status. NEVER just drop items on the ground en masse, and always close doors. I mean always close doors. As for the main menu, that might be a bug from a recent update to the system, as it sounds like you've played before without this issue. Might be nothing you can do about it except clear the cache data and any and all save associated... Obvious issues abound, of course. My suggestion is to deal with it, or back-up the saves and try clearing the cache. Just remember, this may cause you to loss playability with those save, so proceed at your own risk. I'll see if I can come up with anything better.
EDIT: I did a quick bit of research (GOOGLE!) and I guess my original assessment was more or less correct. The emulation seems to cause issues. Though the clearing of the cache data should not cause any game save issues. Try loading a much earlier save if you have one and see if the FPS still takes a hit.
I really must suggest getting a copy on the PC, if you have a comp that meets the spec (That should really not be hard), as it's much more stable, and can be given much in the mod department, including graphical updates. Either way, food for thought.