semiautomatix
Honorary Master
What I have found is that firefox keeps processing flash and animations on web pages if the tabs are not visible. Sometime I find it chewing a CPU core all on its own and taking 500mb ram. Finding the offending page(s) and killing it usually solves the problem.
That I can concur with, though I don't know about the latest version of FF. I had the browser freezing up the entire system with flash animations even though I wasn't using the browser!