I've been running Nightly and experienced the same thing with inbox. If I attempt to interact with it before fully loaded, inbox will freeze up for minutes at a time. Love everything else about nightly, this is my biggest issue.
Would you be willing to provide us a performance profile? Instructions are here: https://developer.mozilla.org/en-US/docs/Mozilla/Performance...
Feel free to email it to me if you don't want to post the link publicly. I'm mconley at mozilla dot com.
Other than that Nightly is amaze balls.
Favoritism isn't the only reason for these things. What often happens is that the website devs all use one browser and nobody tests it.
It's not like Google wants their sites to be broken on other browsers either (I presume), it's just that many teams at Google aren't bothered.
IIRC Firefox has the same WebRTC APIs as Chrome, so this might be reliance on browser-specific nonstandard behavior.
(Or it might not. It's worth looking into, but I can't because it seems like you need to ask for an FB live invite to investigate)
Edit: Figured out how to do it. Seems to work fine in Firefox Nightly.
That is exactly the point the GP post makes. These things are supposed to be standardized and the standards well described, so basic things should work everywhere without any testing. But somehow for web, it is acceptable and accepted as status quo, even after years and years of smashing our heads against the wall of nonstandard, browser-specific features.
There are also cases like where Google's U2F library doesn't work with Firefox's U2F implementation because Firefox's window.u2f is immutable, as a newer (IIRC draft) spec dictates, whereas it isn't in Chrome, and the library does `var u2f=u2f||{}` which errors in Firefox.