TNT explosion causes big fps drop

When I tested TNT cannons for 1.14, I noticed a big fps drop and suddenly increased RAM usage as it exploded, this doesn't happen in previous versions of the game.

What I expected to happen was...:
No fps drop or rise in RAM usage

What actually happened was...:
My fps dropped from 100+ to 4 and my RAM usage went up by 1GB the moment the TNT exploded

I got a friend with a much stronger PC than mine to test this as well, his fps dropped from around 1000 to 5 and his RAM usage rose to 24GB

A video I recorded about it:

https://www.youtube.com/watch?v=BwM0wx2rC3k

 

Here, I shot a wall with TNT but this also happened when no block was destroyed

Steps to Reproduce:
1. let TNT explode (I guess that's it)