A couple years ago I bought the Fallout New Vegas DLC, all 4 of them. Turns out I could only play 2 of the 4, the others gave frame rates of less than 1 fps. Total svcktitude.
A month ago I decided to get the Skyrim DLC. Bad move. My typical move is 1) wait 40-70 seconds to fast move somewhere; 2) spend 5 seconds moving to a door; 3) spend 30-50 seconds entering a building; 4) spend 20 seconds doing what I need to do; 5) spend 30-50 seconds leaving the building. Repeat.
The exception to the above is when I go to the new island the DLC introduced, whose name I forgot, I suddenly go to Fallout rates of 0.5 FPS. yep, that's 1 frame every 2 seconds.
Google says that, just like Fallout New Vegas, the problem is the size of my save file. Well, excuuuuse me for exploring the map and enjoying the game. Not my problem. My last Skyrim save file was 14 meg. I haven't thought 14 meg was "too big" for about 20 years now.
Bethesda, you can svck a petrified dragon dike. I may or may not buy your new games, but no farking way will I ever get svcked into spending money on your DLC ever again.