Earlier quoted context omitted.
The only site I've found behaves terribly in Firefox is LinkedIn. Weird pauses on page load that lock the whole browser (not just the tab) for like 5-10 seconds. No idea what they're doing to make this happen, but it's odd. Which is, well, fine, because LinkedIn is mostly a dumpster anyways.
This prompted me to check LinkedIn after months of having it parked in a tab and it worked with no problems. When I have problems with a site it's usually because I'm blocking most JavaScript with uMatrix and I have to find the correct combination of scripts to make the site work for me without having to give away my soul to the gods of tracking. As a software developer, it's been years since a customer told me that…
Long weird pause.