As someone that jumped ship from how slow Chrome has gotten and went to Nightly /w Stylo and (CPU threads - 1) e10s processes enabled about 2 monthsish ago... Holy damn Firefox is actually fast. Fair comparison, both having Pocket, uBlock, Evernote, OneNote, Pushbullet, and Bitwarden; neither of them having an extension the other doesn't. Above described Firefox Nightly config vs Chrome Dev. Test machines are a works…
I'd like to see the same comparison on a Mac. The Windows version of Firefox has been close to Chrome performance for a while. The Mac version has been significantly slower.
Safari TP 11.1 Release 40 - 62.71
Chrome Canary 63.0.3221.0 - 55.45
Firefox Dev Edition 57.0b3 - 44.17
Not sure whether this would be borne out on later Macs but this seems to confirm my anecdotal experience on my Mac in the last few days, even since 57 came out.