http://www.mozilla.c...x/all-beta.html
In my experience, 3.5.x has been nothing but a pain. From insanely bizzare solutions to slowdown like clearing the IE cache and failing to load on a clean profile, it's just been rather frustrating. A few people I know went off to Chrome and Opera because those would work fine. People kept asking me why I still use Firefox and not Chrome. Well, I find that interface odd, and Firefox has noscript!
But the difference between 3.5 and 3.6 beta is night and day. While Firefox 3.5 would behave like crap with like 5 addons (getting rid of them didn't help anyways) and take up insane amounts of memory if a site uses flash, 3.6 runs pretty swell even after I downloaded a ton of extra addons-- I actually am running 10 now, and yes the 5 previously run are exactly the same. It takes up a bit of memory over time, but it's nowhere near as bad as previous versions. It also has never crashed, which I can't say for the 3.5 versions.
If you don't have any addons installed (noscript will work with 3.6, btw) you should really download it right away. You might be pleased.

Edit: It goes without saying that you should backup your bookmarks when trying something new.
http://support.mozil...oring bookmarks
Backing up other things:
http://support.mozil...our information
But it's best if you are backing up stuff periodically anyways.
Edited by Archon_Wing, 30 December 2009 - 05:07 AM.