I guess I'm posting this because I want to know if anyone else is having the same problems as me. I recently did the quest Blindsighted for the thieves guild. In the quest you go into Irkngthand ruins. At a certain part of the ruins, I began experiencing serious lag, and it didn't stop until I got to a certain point in the ruins, and then it went back to normal. This leads me to believe that there are some parts of certain caves that are laggy.

I am playing Skyrim on the Xbox 360, and would love to know if anyone else has any similar problems.