My fps went down to 1-2 when teleporting to the EnderDragon

I am trying to find my exact spawnpoint, so I decided to go to the end, kill the dragon, and throw an item through the portal so I can find the exact spawn. When I used /tp @p @e[type=EnderDragon] while in the end, it teleported me and I got extreme lag and had to do /kill to get out

What I expected to happen was...:
Teleport to the EnderDragon

What actually happened was...:
I got huge lag and I dropped to 1-2 fps

Steps to Reproduce:
I could not find a way to reproduce the bug in another world