Sorry, have to necro a thread as do not have posting privileges. My issue has nothing to do with the OPs problem.
Yesterday, I started having really low FPS (7-8 FPS) occasionally. Going from the 35-40 FPS I usually experience in SP. It seemed to trigger when I entered the map, and sometimes the Camera or 3D Editor.
I tried lowering my settings, but it did not help much. However when I used auto-detect, my FPS was back to normal even when the auto-detect settings were higher. The really strange thing is that after using auto-detect and getting my FPS back, I can enter the map, get low FPS, and I have to use auto-detect again to get back to normal. Even though no setting actually change.
I have not updated any drivers, are not using any mods and just verified the game. Any suggestions would be most welcome?