Scrolling with startRenderingFromBottom is WAY slower

[billnye2]

Description

The only thing I am changing is whether startRenderingFromBottom is false or true. When false, scrolling is fast. When true, scrolling is slow in the sense that I am swiping as fast as I can and the view is just scrolling very slowly. Not janky, just slow. I notice that once I scroll past say a certain item, if I reverse the scroll direction then it's back to really fast while scrolling in that opposite direction. So like, it's only fast in the zone that I have already visited. Once I scroll back to items I haven't seen yet, then it slows right back down.

I never ran into this issue with old arch and flash list v1. I'm guessing that's because logic is now running on main thread which is slowing down scrolling, whereas before the async nature prevented slow scrolling.

Platform

Android

FlashList version: 2.0.3

[billnye2]

I've discovered that it is much faster to just use the old inverted hack by rotating the list and rotating each item. The list is way faster this way