With 1.13 being released, I have noticed that when TNT blows up, it will decrease your FPS by a lot (as seen in the video provided.) Which is absolutely awful when you're playing a minigame (such as Missile Wars) which uses TNT in it.
I am hoping this could be fixed in future versions, since minecraft 1.12(.2) did not have this issue.
Please do not mark unreleased versions as affected.
You don't have access to them yet.