I just declared Chrome bankruptcy and switched to Firefox a few weeks ago. CPU rarely goes over 10% on my 2017 MBP. With Chrome it was almost always above 50%.
I swapped when the new FF came out. Was sick of chrome using 3–4gb of memory and bringing my computer to a grinding vault. 3 times the number of tabs in Firefox and I have 0 issues. I recommend FF now.
I used Firefox for a couple of years for the same reason, but the new release broke my keyboard shortcuts and VimFx plugin. Now I use opera and cVim, it's even better. Much faster to start than chrome, shortcuts work, syncing works, vim works, developer tools are great, no bloated background services and square tabs!