Originally reported here.

Switching to Classic editor makes the app hang (ANR) for a bit until everything is loaded and then it works alright (scrolling fast and all) but you do have to wait a fair 10-15 seconds for the thing to be responsive. It hangs, goes black for a second, appears (but you can't scroll or anything) and have to wait.

Here's the Post used (it's basically the demo Gutenberg content pasted several times) https://selfhostedmario.mystagingwebsite.com/2019/03/welcome-to-the-gutenberg-editor/

For the record, using the content mentioned here wordpress-mobile/gutenberg-mobile#672 on Aztec makes it take a long time to load and be responsive, same as with the aforementioned Gutenberg post when switching and opening it on the Classic Editor.

On Aztec, switching to HTML mode and trying to add / modify text there is super slow.