RN isn't a wrapped HTML renderer like Phonegap. It uses bridge code to render native UI powered by JS business logic. You still write in JSX, which makes layout pretty straightforward. With some careful optimisation, I had pretty solid 60fps scrolling performance on 1000 item/image lists on old Android devices.
Did you use FlatList or ListView (or a custom module) for this? I've noticed that ListView sometimes does much better than FlatList, interested to hear what you used.
FlatList was absolutely the way to go here. In fact, we initially built the list in question when ListView was the only option. During development, FlatList was made available as an experimental component. It made a huge difference switching over to it. The optimisation we needed to do was to use onViewableItemsChanged to toggle the visibility of images. We found that otherwise it wasn't properly emptying the memory of Android devices, and it was easy to crash older devices. After implementing that, we got silky smooth 60fps everywhere.
