In Minecraft 1.14.4

This is less a bug and more a performance issue.

I had just finished generating a structure, and when I started to tweak the inside of the building, I noticed that every time I broke or placed a block, the game would hitch. I've attached a picture and two gifs. The first gif demonstrates the ~40-50 fps i have placing a few blocks just outside of the structure, and the second is from within the structure, dropping the fps down to 6. You can see the fps count in the top-right corner.

First Gif

Second Gif

Thank you for your help and the work you do on this great mod!

Oh goodness, and now I feel dumb. You know the "Did ya try turning it off and back on?" trick?

Well, I saved and closed the world and started it back up -- and everything's fine.
Slams head on desk

Case closed.