Yeah, firefox has been a pretty abysmal experience for me on android, it's slow, scrolling is janky, it crashes almost every time I try to use it... it's just been a bad experience all around.
as mentioned elsewhere in the comments, it's a good idea to set up the default browser in android to use the maximum of privacy and security settings together with the uBlock Origin addin.
these urls provide some good starting points :
https://www.linuxfestnorthwest.org/2017/sessions/security-an...
https://www.privacy-handbuch.de/handbuch_21.htm
the 2nd url is in german but it has great tips (spurenarm surfen = surf without leaving traces)
If you're willing to give Firefox another chance, it's a good time to do so. They've put a lot of effort into performance in the last few releases.