How do you compare browsers you've tried in terms of resource usage and efficiency since CPU usage might not directly correlate with it given there are other factors almost always at play?The problem is not youtube.
The thing is that e10 of FF is using more CPU on every site i am visiting i comparison with chromium.
I am using extensions to change that but i am not satisfied with the results i am getting.
So for the moment i am sticking with Cent.
When the new version of FF comes out i will surely try it.
As for Edge i can't say much about it's performance because i don't use it very often.
Firefox, I found to be very volatile with extensions. Extensions could really slow it down like restoring a lot of tabs and make it a CPU hog. WebExtensions would force good addons to be less volatile and bad addons from uncommited developers to die out and Chrome should also benefit from this.