For me, I have found Firefox to drain my laptop's battery more (Macbook Pro, 2017) compared to Chrome (and Safari). Once it changes, I would gladly go back to using Firefox.
Firefox has been hilariously bad for Macs for as long as I can remember. I refused to touch for over 15 years because it was incredibly slow each time I tried. Now that I'm trying to get out of Google's sphere of influence, I'm kind of forced back into it (Safari just doesn't feel right to me). Speed seems much better than it used to be and I can't really tell any difference between it and Chrome. Memory usage is an…
Can you please file a bug at https://bugzilla.mozilla.org and include an about:memory dump? You'll probably need to report what addons you have too.