Its not always just the browsers if you hard disk is over 60% full it will slow down markedly. If you want to post a list we`ll tell you which ones you can safely delete.
For what it's worth, I use Chrome as my browser except for some work sites that only work on IE - this is really slow and a pain so I go there as infrequently as possible.
My Firefox was very slow recently and I noticed it was showing several times when I looked in Task Manager. I used this link to fix it:-
https://silicophilic.com/disable-firefox-multiple-processes-task-manager/
It might be worth a look at your Task Manager, to see if the same thing is happening.
Thanks for that reminder about limiting the number of Firefox processes, Mrchirpy. I've used it in the past to speed Firefox up but I'd forgotten about it.
I've just cut the number of processes from 8 down to 2 on my (elderly) PC and there does seem to be an improvement in speed. (I'll have to remember to keep the number of tabs I've got open to a minimum though. I do tend to have too many open at times!)