Are you using a non-native display resolution? That seems to be the common factor for people who have significant problems.

https://bugzilla.mozilla.org/show_bug.cgi?id=1404042

A scaled resolution is now default on most MacBooks. I haven't noticed battery problems but certainly seen RAM usage at least double that of Chrome and considerably above Safari.

If you are worried about battery performance, I can personally attest that Firefox is better than chrome in terms of battery performance.

Still Safari is the best in terms of battery endurance (its a VERY SIGNIFICANT difference). But then again its Safari, so you have to decide whether you want a capable browser (FF/Chrome) or a battery efficient one.

IMO Safari is a very capable browser. I switched to it long ago and found I didn't miss anything from Chrome. Experimenting with Firefox now because I love the containers feature, I hope we'll see it in Safari some day.

In my personal experience, other than Apple crippling the extension feature by moving them over to the App Store, Safari is a pretty damn capable browser. It's actually been rather interesting to see drastical improvements in it yearly, even the Mojave build's come with a serious performance boost. Firefox overall feels a lot slower than Safari with some exceptions. The only major killer feature I've noticed is the Devtools on FF.

Safari is my main browser when I am not working with frontend stuff and it's perfectly fine.

What do you mean by performance? I’ve found Firefox to be generally faster than Safari and Chrome on my MacBook Pro. I generally find it to be more energy efficient than Chrome, but Safari is still king there.

This is personal experience, no lab tests, etc.

Regarding the other replies, I believe that Firefox is extremely slow in OS X only if you use a scaled resolution.

That seems to be a known issue, but for some reason it's taking a long time to be solved.

Scaled resolution is default on most/all retina MacBooks which is unfortunate.

For me it is only slow if I go outside the default scaled resolution. On my 2015 13" mbp I use the default scaled resolution to get around the performance issues.

Another work around if you want to use a non-default scaled resolution with firefox is to use firefox in non retina mode. I prefer not to use this as it makes the experience blurry.

I do wish they would fix this issue though.

Oh ok, great. For me the default scaled works best visually and I don’t use an external monitor so glad I won’t have this issue.

With the handoff working too I’m downloading tonight to give FF a fair shake.

I wonder if this is due to not using the native compositor which they are looking at fixing this year.

See "Adding support for native OS compositors to WebRender" at https://pcwalton.github.io/2018/12/07/plans-for-2019.html

Had this issue... until this version! I'm using MBP 15 inch with Firefox 65 (Beta channel), it doesn't use as much CPU as it did before, and it doesn't suck up all battery. This is on scaled resolution of 1920x1200.

It’s strange - I could have sworn that, for a while around where “quantum” was released, OS X performance was really quite good. I ditched it for chrome for a bit, and it even held up with my daily 20+ tabs.

It feels slow because UI is not native. Chrome, Safari, Opera have native UIs on macOS. I mean they are rendered by macOS instead of browser engine. You get 60 fps for every action which doesn't happen with Firefox. Maybe they should use a process just to render the UI.

It's definitely much improved in the last few versions (64/65). Probably still quite power hungry, but it's not making my fans spin up anymore...

Try Firefox Nightly. Runs super smooth on my Mac, and I think WebRender is what solves this for many people.