At the risk of a downvote storm, a few months ago I tried to switch from Chrome to Firefox until I had a call of two hours via Google Hangouts and Firefox started to degrade the voice until a point of no return. I don't know if this is common in very demanding "web apps".
Once Google finishes killing off Hangouts, maybe you can give it another try. Google has no incentive to fix performance issues for competitor browsers in a product that is end-of-life.
I've noticed the same sort of "degradation" when having large PDFs open as well. I have to refresh the "page" (the PDF) to be able to search for something and find that something that I know is in the PDF. Small F5 issue once you know about it cause it remembers where you are in the PDF.
My guess is RAM management/garbage collection going on in the background that needs to whitelist a few things or have some additional fancy stuff going on to not allow for memory leaks but allow for 2 hour phone calls and searchable PDFs after they've been open for some time (and possibly with a 10+ tabs open).
Definitely file a bug. I would imagine both these issues are known about and have a similar root cause.
Blame Google, not Mozilla. They're doing it on purpose and it's the main reason why more people should make the switch now before it's too late and nothing else works with Google's stuff but Chrome:
I don't have any proof for this, but I think everything I've seen about Google's Invoice was also meant to kill the open email standards by convincing everyone that the proprietary "AI-enhanced" features of Invoice were worth it over interoperability with other email providers.
Thank goodness that app failed. They're still trying to do it through Gmail now, but it's going to be a much slower process and hopefully people will have enough time to catch on to them before it's too late.
Google is becoming a monopoly in the classical "evil company" sense - a monopoly that's no different than any other monopoly in the past, and that will try to exploit the users and kill competition in the same way others have done it before. More people should start to seriously consider this before going more "all-in" with Google than they already have.
