0xChat gets a bit laggy on some Samsung phones (they're the only brand I use and have tested) and seems poorly optimised — perhaps the "pretty" stylised interface makes it slow when opening tabs or with many contacts, I can't say for sure what's causing it. When I open new profiles with no bio, no NIP-05, no contacts, just a profile picture, the app works perfectly, even on an older phone. But when I open my profile, which has many posts, NIP-05, a description — particularly with Amber — the app becomes extremely slow and freezes. Sometimes it even crashes.