I’ve been using both Firefox and Chrome since they came out and they have always felt near each others performance. It would be interesting to see some data on the subject.
Now I use Brave, and it's cool, it also encourages you to use interesting stuff like IPFS Companion, which I didn't know existed for Chromium until I switched to Brave.
I think even if Google ruins Chromium, it'll continue in the open somewhere else, and still be better than Firefox at the things that are important to me.