Of note for those using Wayland/Mutter Firefox 78 now has the option of Partial Present[0] and better supported VA-API for video playback.

Interestingly there was a recently discovered Mutter bug[1] where the Culling code to prevent rendering of windows that were not visible was not working. This fix will need to be deployed to see the biggest benefit of Partial Present.

[0] https://bugzilla.mozilla.org/show_bug.cgi?id=1620076

[1] https://www.phoronix.com/scan.php?page=news_item&px=GNOME-Br...