Significant lagspices while moving between chunks

What should happen:
When I walk or fly through any 18w43a or 18w43b world I shouldn't get any performance issuse.

What happend:
When I walk or fly through any 18w43a or 18w43b world I got significant lags while I walkt through chunkboarders. I cheked my memory, my cpu and my gpu, but nothing was wrong.

What I've done (Step by Step):

1. I've generated a new World
2. I walked and flew through the world
3. I got instant lags, as I moved through chunkboarders