I’ve been using FF for more years than I care to remember, and with the exception of a couple of sites that weren’t really that important, I’ve never had an issue. I certainly never had an issue running uBlock Origin and YouTube.

I flat out refuse to use anything even loosely based on Chromium on principal alone.

Been using FF since forever, never felt my experience was in any way slow compared to Chrome.

I never stopped using Firefox, and I never had a problem with anything but Government sites.