Really? Huh. I'm surprised other people's experiences have been so different. There are tons of forum complaints about the problems I've had. There's even an official faq about all the tabs going blank [1], which tells you to restart the browser and hope it goes away. Mozilla themselves gave up on the whole codebase two and a half years ago and started work on Firefox Preview/Fenix instead [2].
FWIW, my experience is exactly the same. Zero problems, snappy, supports uBlock Origin, does not contain Google spyware and I therefore vastly prefer it to Chrome.
When I first heard of people complaining that it is atrocious, it was as much news to me as it is to you that it is excellent in my experience. I agree it's a weird phenomenon.
[1] https://support.mozilla.org/en-US/kb/firefox-android-display...
[2] https://www.xda-developers.com/mozilla-transition-users-from...