I keep on crashing when i about to enter the world i made

Put the summary of the bug you're having here

What I expected to happen was...:
When i start a place on Minecraft i wait for about 3 mins.

What actually happened was...:
That it crashed on me when i click create world.

Steps to Reproduce:
1. Go to mane menu
2. Click create world
3. Then it crashed after waiting for about 3 or 5 min.