Um, of course that the time to upgrade has come (and gone).
Unfortunately Mozilla had decided that webextensions are the way forward… Not only that, but the new(er) versions (edit) of Firefox are simply atrocious with bringing bloatware and compiling components which have NO business (whatsoever) being part of the system and should’ve instead been developed as plugins, or something.
Having said that, what are you going to do with a 2-3, 5 year old browser - down the road? Might as well look up a copy of Netscape, then.
*Firefox still remains bearable through (extensive modification of) about:config settings, for as long as Mozilla will allow it. We’ve seen how Google Chrome is hard-coding what used to be available through chrome:flags and, fingers crossed, hopefully this’ll never happen to our favorite browser; no matter the “market conditions” (or whatever, blah)