Some people have voiced reservations about Firefox’s latest releases — reservations regarding issues like bloated-ness, crashes, and overly fast releases. I myself find since Firefox 4, Firefox has been crashing a lot although stability has seemingly improved since Firefox 8. If you are one of those people that would prefer “the good old days” then you will be happy to hear Mozilla is still supporting Firefox 3.6.x.
Firefox 3.6.x obviously doesn’t have all the new features and “improvements” made in later Firefox releases, but Mozilla has pledged to continue to provide security and stability updates to Firefox 3.6.x “for a short amount of time”. How long is this “short amount of time” is unclear; what is clear is that you can grab Firefox 3.6.x (3.6.25 at the moment) if you are unhappy with the newer versions.
And, yes, you can install Firefox 3.6.x alongside your other Firefoxi, if you so wish it.
You can grab Firefox 3.6.x from the link below. It is available in multiple languages and for Windows, Mac OS X, and Linux.