Well, I usually don't have more than a half dozen tabs open at a time, but I sure have noticed over the last year or more what a memory hog FF has become. It's always using 1-1.5 gig with me by the end of the day. I've always figured it was memory leaks, but I guess it could have been bad coding and bloating as well. I'll have to monitor after the next update to see how it performs.