I don't know, whether this is some kind of bug or whether this is caused by a bad configuration: I recently installed Elyssa, and with it the new Firefox 3. I'm really satisfied with it, it loads pages faster and has some other nice goodies. But when it comes to scrolling up and down a page, it seems to be quite slow. I also tested FF3 under Windows, where this doesn't happen. I compared it with Opera, which also seems to be faster. I tested Swiftfox, a cpu-optimized version of FF, and it is quite the same problem. Maybe this has nothing to do with the software itself, but with the graphics driver (ATI 9600 with the nonfree driver), because I also have problems with playing videos smoothly.
But I really don't know and would appreciate any help.