Recently made the switch to Mint from Windows. I am having a problem with FF though. Randomly but very frequently I see your most basic page load very slow if not at all. I have disabled hardware acceleration as some research has suggested but it still has the same issue. This happens on both my laptop and desktop.
xdg-desktop-portal-gnomecrippled my install as well - both Firefox and Steam took an absolute age to open. Uninstall it, everything perfect again.