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.