I never used Firefox 3 before, never took part in the beta or even the RC. So, based on first impression, memory usage has actually been improved and its even below Opera 9.5 on my machine. However, Opera's speed completely beats this. I've tried clearing the cache and everything and tried loading a few different websites at a time. Opera wins by a clear margin. But, I recall that firefox becomes a little quicker with fasterfox and a few about:config tweaks. I'll try the comparisons again tomorrow with the tweaks.