The energy usage tab on the activity monitor consistently shows Firefox at a ~40 “score” (whatever that unit is), and Safari more around 4. Anecdotally, the difference in battery time is real.
This is the biggest reason to keep using Safari on Mac in battery mode. (Or Always Be Charging :) )
I hope they can ever fix this :( sounds pretty fundamental, but I know little.
Also, being cross-platform complicates things a lot: I'm certain that Safari has access to a number of libraries that are energy-efficient but exist only on macOS/iOS.
I have a vague hope that maybe the Rust community can find a way to somehow develop a standard benchmarking tool that takes into account energy use. This would help considerably on the front of refactoring Firefox towards better energy efficiency.
- Battery draining...it's seriously really bad. Even if the app is just open on my MacBook, I go from ~8hours of battery to like ~2hrs. I travel a lot...it's untenable
- Performance is generally pretty good, but it never felt better than Chrome.
- At first CPU on streaming video (Twitch, YT, etc) was better on Firefox, but over time I got the infamous "fan spinning" and CPU churning issues.
- Site compatibility: about 10-15% of sites I would visit broke.
- Nitpick, but not deal breaker: icons on my bookmark toolbar didn't work consistently. I would save a bookmark and it would stick to some other site and I could never clear the cache to fix it. It also frequently used non-retina images.
My measurements are that on some specific pages, even when I "do nothing" Firefox uses up to twice as much CPU. Luckily, it's not always twice as much battery drain, because even idle uses power. But it's definitely visible and measurable: from 3 hours of other browsers you'd probably have only 2 of Firefox.
You know you're old when you hear people making references to Godzilla in the 90s :-)
I need someone to make a case that FF dev tools are better than Chrome, simply because without performance being an issue, I need confidence that switching would be a net productivity increase despite having to learn the slightly different tooling of the FF dev tools.