OK, I personally have been using FF since the beta days and really love it. I loath chrome, think Opera is meh, and think IE is a steaming pile. However, as time goes by I have noticed that FF has gotten less and less stable with each revision. Plus they have NOT fixed the memory leak, and it too has gotten worse. About 2 weeks ago I got so frustrated I started looking for an alternative…and found one: WaterFox.
Unlike FireFox, WaterFox is 64bits. This means that the memory leak...does not matter. Usually FF craps the bed when you hit about 140 tabs open - or 3.5'ish GB of mem usage...which ever comes first. I have had 400 tabs open on WaterFox, had it pegged at 15.5GB of memory usage without problems.
More importantly it has been rock solid with zero stability issues.
As an added bonus its built off the FF code base (recompiled for 64bit and for the OS with some low level tweaks to improve stability) so you dont lose your profile, your addons, your history, your customized layout...or anything else. Hell as each new FF is released a WF gets released basically the next day! Better still it actually uses (by default, but can be changed) your FF profile so you can switch back and forth between WF and FF and backup with Mozbackup. You just cant open FF and WF at the same time...it will simply open a second window of whichever program is open at that moment.
The only hitch is you need to use compatible add-ons. I have had exactly one add-on need to be reinstalled and that was as simple as finding the 64bit version BUT that was it. All the rest worked perfectly...just as if it was FF.
I can honestly never see myself going back to vanilla FireFox. Of course YMMV and backup your profile before you mess with it...but it might be worth a twirl.
Oh and Im in no way associated with WF or its developers....Im just a (super) user who thinks others might like an improved Fire(d)Fox experience.