[neogodless]

What OS, hardware and video platform(s)? I haven't had any issues with Desktop Firefox on Windows 10 on any of my Core i7 machines, when watching YouTube/Vimeo. Even my old dual-core budget Inspiron 3137 laptop works for YouTube and Firefox as well as Pandora/Firefox/bluetooth audio blasting.

(It does like to consume RAM as if it was running SQL Server though.)

[Passthepeas]

It happens both on my Mac Book Pro and my Windows 10 desktop. I don't have the problem as much with pre uploaded videos but with live streaming sites like twitch.

[tzakrajs]

Also having a good time with Firefox on macOS running on an early 2018 MacBook Pro. It has fully replaced my Chrome use at work.

[AsyncAwait]

Same here on Arch Linux for me.