Lately I've been moving away from Google everywhere I can. I moved everything but Google Voice. Yes, even Google Search - I've moved to DuckDuckGo. On windows however, I had to fall back to Chrome, because I was just shocked at how slow Firefox was.
Opening pages like Twitch.tv proved to be shockingly slow. Furthermore, my habit of opening many tabs in the background like I do in Chrome/Safari was massively slower in Firefox because while Chrome doesn't autoplay new-hidden tabs, Firefox does - I imagine Chrome feels faster there because it's not running nearly as much stuff at once.
Pretty much everything of Firefox felt slower for me. And this is from someone that really wants to get away from Chrome! On OS X, I've long switched to Safari and DuckDuckGo, and been quite happy. I've had zero complaints about performance with Safari.
So.. I don't know what they need to do, but I'm really hoping they do something.