now that's just rose-tinted glasses speaking. I remember how absolutely abysmal old Firefox' scrolling was, and how they've claimed multiple times that they've improved it but it was still horribly sluggish compared to Chromium browsers. I've been using Firefox Preview (and then Nightly after enough performance improvements have landed on it) for about a year just to have acceptable experience on mobile.
Honestly the one thing I don't like is how pages constantly refresh when you alt tab (or w/e the equivalent is on Android - swipe tab I guess?). I know it's a small thing but it just gets at me. I also like the old UI as it was more Firefox-y; the new one is too white and plain.
I do miss the tab bar, it would be great to have it on the tablet. I can't comment on how differently the browser behaves now regarding storing loaded pages in memory though, because most of the time I'd have an underpowered phone that would kick out everything out of memory when switching apps anyway.