https://bugzilla.mozilla.org/show_bug.cgi?id=909760 and https://bugzilla.mozilla.org/show_bug.cgi?id=1104146 are the issues for downloading which are 4 and 6 years old.

Chrome and Safari support keyboard multimedia keys to play/pause video and audio which firefox does not. Picture in Picture is not available on Firefox.

Pinch and double tap gestures to zoom are not available. Scrolling does not follow system conventions like overflow kinetic scrolling.

https://pcwalton.github.io/2018/12/07/plans-for-2019.html mentions about excessive power consumption on webrender.

> Pinch and double tap gestures to zoom are not available. Scrolling does not follow system conventions like overflow kinetic scrolling.

I find this hugely annoying as well on MacOS when using the touchpad. This is also the reason why I stick to iOS instead of going for Android. All of these details are great on my laptop and phone, though they're not what I really need on my desktop.

Ah I see, I guess I don't use any of that stuff myself. I tend to move between macOS and Linux, so I don't get too attached to system specific shortcuts. That said, I really don't see any of these problems as being show stoppers, and I haven't noticed much difference in battery usage between Chrome and FF.

2015-01-25 Support elastic overscroll (rubberbanding) on macOS: https://bugzilla.mozilla.org/show_bug.cgi?id=1124108