I used to use Firefox and no other.
But every once in a while they do something to their browser that makes it really sluggish and it takes a long time for them to fix it.
So I got fed up the last time and decided to try Chrome (in spite of the fact that I really dislike Google because they're too damned good at being snoopy).
After a while I learned that Chrome can get really sluggish also.
So I installed another add-on that allows easily clearing both cache and history. That very often speeds up both Chrome and Firefox. In fact, sometimes I can't load a page at all and keep getting error messages telling me to push the button to try again. That never works. So I stop all downloads, delete the tabs, clear both cache and history, then everything works just fine again.
At any rate, NoScript is a good thing to add to Firefox. Also useful is a button to clear cache and history at any time. And I think I heard that there is now a version of AdBlock for Firefox, but I could be wrong.
I also set the browsers to clear both cache and history every time the browsers shut down. That helps a lot. I prefer to keep history longer, but speed is more important.