As I was about to ditch Firefox...

If you've come here, you have most likely experienced annoyances with Firefox.  (In fact, you've most likely experienced them even if you haven't come here.)
Like, it being so mastodontically slow that it took more than a minute just to load, and then it had to think and ponder for a few moments - actually, more than a few - before executing every single command you gave.

Well, I have.  I've been using Firefox - along with four other browsers - for ten years now, but in the past three or four years it has become impossibly slow, practically unusable.

So I tried to find a solution. There is an add-on called Memory Restart that gives you the chance to restart Firefox with no hassle every time its memory usage bloats out of proportion (and that happens very fast with Firefox... in fact, that's the ONLY thing that happens very fast with Firefox). Unfortunately or not, it was made by Mozilla and it only helped me very marginally. Very, very, very marginally.

So I searched on. 
I found a thread that suggested deleting all "sessionstore.JS" files and its duplicates, if any. You can find them in your profile. 
(Click on HELP, then TROUBLESHOOTING INFORMATION - or just follow the instructions on this page.) Or you can do what I did - because it's the fastest way - and simply search your computer for sessionstore.js. To find them, you'll have to have the "search hidden files" option enabled, of course.)

Again, it helped. And again, only very marginally.

Then - to make a long story  much shorter - I decided it was probably one of the add-ons that was causing the slow-down-to-crawl.
So I opened my add-ons folder and disabled the most obvious suspect: ADBLOCK.

It worked like a charm.
Sometimes the most obvious suspects really are those whodunnit.

So, think - as I failed to for much too long - what benefits, if any, does AdBlock bring you, and are you willing to sacrifice normal-speed browsing for the pleasure of not having to see a few ads.

I am not.



ADDENDUM (June 2, 2013):

Well, for some reason the "charm" only worked for a day.
Today Firefox is back to its old form: bad, slow and very tiresome to know.

I mean, it still is better than before - especially after I deleted the storesession.js again - but it's nowhere up to yesterday's speed - not that it was lightning-fast or anything (we're talking about Firefox) but it was much faster than today.

Don't worry, I'll keep you updated.