Entire Bible (4 mil chars) in a note -- What is your ultimate challenge for notetaker?

Following notetaking journey of Robert Lender I found out the recently he stress tested Joplin by inserting entire Bible: text 4.281.085 characters long

This led me to wonder, what other challenges or stress tests do users put their note-taking apps through before fully committing to them?

How do you know your chosen app can handle your unique needs and demands?