Matias Seppä

I also had same issue. I recommend to play on 19w46b and change to 1.15pre- 2 when it's released. 

You can just play in 19w46b or lower and move yourself and play on 1.15pre-1 again

I had same issue in vanilla singleplayer 1.15-pre1. When I try to join to the world again fps drops down to 0-1 and game crashes.