Minecraft Crashes When Switching Between Worlds Quick

Put the summary of the bug you're having here

What I expected to happen was...:
It Would Switch Worlds Just Fine

What actually happened was...:
Is Crashed After Switching Between Worlds Quick

Steps to Reproduce:
1. Create Two Worlds Name Them Anything
2.Switch Between The Worlds Not Very Fast But Fast Enough You Are In It For 5-15 Seconds
3.And That Might Work Might Not If It Doesnt Sorry!