Did your Firefox get down-graded the slower version 57.0.0? Yes SLOWER! It's all over the internet NEW FIREFOX SUPER FAST! Well not so much, you lose the Classic Theme Restorer which made FF pretty fast! You get stuck with tabs above the address bar GRRRR...
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I ran all of these and it was slower in everyone of them. And in Linux you can't just roll back it's a whole delete, purge, unzipped, copy to, allow to run as... more