If you didn’t know already, today is Download Firefox 3 Day. They’re trying to set a World Record for the most downloads in a single day. I read somewhere that the fun begins around 10:00 a.m. PST.
I’ve been runing the pre-release versions for a while, and I can confirm that the memory management and speed are much improved. I normally have about a dozen tabs open at any given time, and I occassionaly have had 40 or 50 tabs going. In Firefox 2, this would cause major memory problems, even after I closed the tabs. But FF3 handles it well.
If you’re worried about the compatibility of your current add-ons, try installing the Nightly Tester Tools add-on, which lets you override the version checks.