I've been using Firefox Nightly (57) for a while on a 2013 MBP running Sierra. Firefox definitely feels significantly faster than it used to, and the new UI is great.
But this comes at the cost of battery life. I moved back to Chrome because it was constantly chewing CPU.
But Chrome is also guilty of absolutely guzzling battery. I always try other browsers on macOS but in the end keep switching back to Safari because it easily gets me ~2-3h more battery life. This means that on 10h average battery life you'd pay a ~20-33% battery life premium just to run a different browser. At that point, finding replacement Safari extensions is well worth the bother.
What I don't understand: why is it that other browsers don't put battery life before all else? We live in a portable world after all..
I switch to Safari when on battery. But the cost is pretty high - it's the only browser I have on my mac that I find actively unreliable, and the feeble range of available extensions makes it seem crippled compared to Firefox or Chrome
+1 for the significantly improved performance on Firefox on OSX (I'm on a 2015 MBP), not just in the current 57 nightly, but since Firefox 55 came out.
Yep, switched to FF from Chromium since 54/55 when multi-threaded tabs became default. Don't need to restart once in a while when Chromium has eaten up all the RAM. The extension support is just as good, and some of the labs features are very interesting.
But this comes at the cost of battery life. I moved back to Chrome because it was constantly chewing CPU.