[CWuestefeld]

I'm sure it is an extension. The thing is, I can't easily figure out which one. Since it takes a couple of hours for the problem to occur, it's too much of a big deal to try a binary search of all extensions to figure it out.

Compare to Chrome, which has its own task manager, which shows CPU and RAM usage of each extension.

[ajanuary]

I remember reading that FF now has something similar. It might be in the nightly or a plugin or something though. Unfortunately I can't find it now :( Sorry