Earlier quoted context omitted.
What does "faster" mean? honest question. I've been using Firefox since its early days and never jumped on the Chrome bandwagon simply because I didn't see the need to do so. When Firefox felt slow, it usually was the whole operating system that's slow and neither Chrome or any other browser could solve that. Nowadays, all the machines I use are powerful enough to not feel any such slowness and I just don't understan…
Not OP, but what I think is that FF renders the twitch.tv page very slow. On macOS, not just the tab but the whole FF app locks up, showing a spinning beach ball. It's the only site that I found that does that.
Speaking of Flash, some sites request Flash on Firefox but not on Chrome for example (although it's totally unnecessary). This is becoming less frequent recently but it shows that a lot of websites are not taking advantage of Firefox's full features as they do with Chrome (something to consider as well).