Firefox is still cutting my MacBook battery by 1.5 and often munching through 30% of cpu on many websites, with or without extensions and adblocker. It’s a shame because I love the browser in every way than the rest of the browser gang.
Opera for when running my laptop on battery Vivaldi when in the office.
Now, I've ditched Vivaldi and sticking with Opera & Firefox.
I suspect someone will create a Firefox Addon to auto-detect we running on batteries and throttle back on the performance settings.