Didn’t want to set up an account on bugzilla, but I wanted to add a comment. I *think* 50% CPU on a dual-core OS X system means 100% of one core. So if the reporter is at a little over 50%, that means one thread is pegging one of his cores. Depending on what kind of ops it’s doing, that could easily kick the temperature into the stratosphere. Just wanted to get that said, to make sure people are looking for the right thing: a spinning, hard-working thread.

Someone (with a dual-core) should verify the 50% = 100% of one core thing.

Ben Morris, also from that crowd, reports that Firefox (all versions) on his Windows box also burns silicon, but at normal low CPU usage, even with no windows open. The chip just gets very very very hot while Firefox is running. Likely irreproducible.