All modern chromium browsers have animations when opening tab view and gestures like closing a tab with a swipe (instead a small close button on ff). I'd love to see some animations and use of gestures on Firefox android.
I guess your idea was not good enough, as more than 1 year later we do not have basic animations. Of course Mozilla feels choppy when comparing with any other applications.... 😔 Although it is visible quicker, I see shutters all the time. This makes me feel like I want to use Brave or anything similar...