I've been on FF Nightly for the last couple of months but recently switched back to Safari. On a MacBook 12" (i5) Firefox did terrible things to the battery lif

I've been on FF Nightly for the last couple of months but recently switched back to Safari. On a MacBook 12" (i5) Firefox did terrible things to the battery life and generated enough heat that I'd often find the CPU throttling. Neither Safari or Chrome have the same issues. I haven't really tried FF since the nightly jumped to 59 but I keep it updated and occasionally check to see whether this has been fixed.