S20 was released before the pandemic, on Feb 2020. So, its just 3 months away from being 4 years old. It's old. Most importantly, this CPU was released before the UI Framework we use (Jetpack Compose) and doesn't have any of optimization for it. I am not sure there is much we can do.
Discussion
Yeah I'm bit in denial about it being an old phone.
But the fact is that flutter code can make it quite usable.
Can you confirm if primal native android code is not using also jet pack composer? Because they're also quite fast UI on my phone. Maybe it's not a jet pack compose issue but something related to how amethyst uses live data or similar, I don't remember exactly what was the problem. It's on some github task comments...
It's about the number of components/clickable components in the screen/each note. The more you add the worst it gets. We might have added too many. :(
I did try to comment most of the feed components on amethyst's code and leave just a simple list and it still was not fluid enough. That's why I suspect something related with how data listener/consumer model is handled.
On my S19, I have to remove the rich text of posts + relay icons + turn most of the SVG icons into bitmaps to run smoothly. In the notification, I have to remove the clickable element of each of the author pictures. :(
Of course, if we can minimize the processing of new events, that helps as well.
I am currently refactoring the base caching system and the new one should help, but it is a lot of work.