What size is your game save file. Over 10MB and all the freezing and lag pop up. About 12MB and higher it becomes unplayable, especially at Adam's Airforce Base, Capital Wasteland, Bailey's Crossroads, Point Lookout, The Pitt, Mothership Zeta, basically anywhere that was added by the DLC. Of course in Vanilla Fallout 3 I always had freezing issues at Tenpenny Tower between levels 10 - 16.
By the way you will never see another patch from Bethesda to fix this. They are dropping all their time into Skyrim and the new Creation Engine. I'm going to sit back and wait until I hear from these forums how the Creation Engine is holding up before I even think about purchasing Skyrim on any console.