I own a no cheats survival realm where I have a pretty big community the realm is full of 11 players most of the time. The realm tends to lagg before the crash which I understand lag is to be expected with 11 people i guess but I feel like the realm crash is because of the lag. It's like the realm will fail to create another back up of the realm so it will crash and role back to the last auto save. 

How to replicate 

1.Let the realm make a back up 

2. Then do alot of things to make the world size over 50 mb 

3. Wait for the realm to make a backup.

Then most of the time it will crash causing it to use the last backup.