Earlier quoted context omitted.
IME Firefox (esp with the right extensions, like autosuspend tabs) is very light on system resources. A bit more so than chrome. I run only Linux though. All the "websites that should be a program" (Netflix, Hulu, Slack, Amazon Video) now run great in FF, without my computer overheating. (though some of them might be on the chopping block if they don't quit blocking me from seeing HD content) I hear Apple does some s…
Honestly I do not think Apple does some special magic on Mac OS for Safari. I settled on Vivaldi (a chromium based browser with built-in ad blocking developed by former Opera devs). It gives battery life not much worse than Safari to be honest. Safari is very nice and snappy on a mac, but the extension support is extremely limited.
It also runs on iOS, even with extension support!