OK so after having firefox open for about 30mins or so every 10 seconds or so it will totally freeze for about 2 seconds, then unfreeze and keep doing it.
Right now firefox is using 85,248K with just this one tab open! Processor use jumps around madly while scolling, but when firefox freezes it drops straight to 0 for a second or two, then firefox unfreezes. This is a pain in the ass, i've tried re-instlling firefox but it made no difference!