Steps to reproduce:

1. Create a Gutenberg post on the web with Gutenberg demo content using a variety of blocks.
2. Add about 10,000 words.
3. Try to open the post in Gutenberg in the app.
4. If you can open the post, try scrolling.
5. If the post gets closed, re-open and try scrolling again.
6. If you can open the post and scroll, then try editing any block.

Result: triggered the ANR dialog trying to open the post in Gutenberg in the app.

/hat tip @rachelmcr for the original report at wordpress-mobile/WordPress-Android#8628.

(internal ref: p4a5px-2iV-p2)

I tested and confirmed with Pixel 3, Android 9, WPAndroid alpha-153 (11.9 alpha) using self-hosted site alleged-swift.jurassic.ninja running WP 5.1 and Gutenberg 5.1.1.