Quickly put: I have played the game completely through with all of the expansions. I didn't - on the first or second time through - notice any issues with lag. Now I'm on who knows what number character, but I noticed that one day I would get SEVERE lag in certain places. Namely: Colovian Trader, Rosethorn Hall second floor, Chorrol's Chapel Hall and - it is by far the most severe lag - Sheogorath's Palace and Sinderion's Cellar. (there are many many others) I walk into these places and it's almost completely impossible to move and takes quite a few clicks before the mouse ever registers something. The only way I can usually even get out of them is to look down on the ground when I try to move and hope for the best. I attempted to "fix" my saved game thinking it was perhaps the A-bomb, but the "fixed" save isn't working any differently. (I'm working with a save that's right outside of the Palace and once I go in there, even with the fix, I can't move. I also have increased lag, sometimes severe, in the courtyard.) I've noticed that it's usually -but I guess not always because of the Chapel Hall - related to having fire in or near my line of sight.
I did mess around with different settings for the graphics just to see how my computer would run with them, and I *think* that's when I noticed the change. But I uninstalled (that was an adventure on it's own) and then reinstalled the game and all expansions thinking maybe it was a setting, but when I started the game up again, it picked up where I left off. Obviously the uninstall doesn't clear all the files/registry entries?
Anyways, any help would be appreciated because at this point, I can no longer play and I'm at a loss.