I don't really have any issues with Fedora performance wise, is it widely perceived to not be performant? I have had much more issues with everything on Ubuntu than I ever had with Fedora. Maybe ricing with Gentoo could get me a bit further but given both Firefox and Chrome will basically use the same system libraries I don't see how it is fair to blame Fedora for the difference.
I've been running FF on Fedora for the last 14 months with no problems. I typically have 20-40 tabs open, but then again, I'm also using NoScript so maybe 10-20 of those tabs are not doing so much damage to my performance. (The ones that stick around, like 4 Gmail tabs, Slack, RSS reader, etc. are whitelisted)