Re: Put it out of its misery
I'm a long time* user of Firefox who found that all of my 'necessary' addons work just fine in the new version, so I've stuck with it.
I've also never had a problem adapting to the new interfaces they've unveiled over the years.
I've always found Firefox to be as quick, and use about as much RAM as the available alternatives.
Thing is though, people who are happy tend not to start complaint threads in semi-related news stories so you might have got the wrong impression.
(* Phoenix 0.4 I think)