Ghast on ground causes lag

I found that when a Happy Ghast is tied up to a fence post, and floats down to ground level so that it’s tentacles phase into the floor, it lags the surrounding area.

Our realm after the update at some point became laggy around our normal house area, not always, but a lot.
I discovered it was only in that area, and decided to gather some coordinate points to try to triangulate where is was coming from.
So after gathering about 20 points that were on the edge of lag/no lag, the middle point was in a spot near a lot of natural cherry blossom trees, so after removing them to no progress, my next guess was the Happy Ghast I had attached to the top of my house.
After moving it away and attaching it’s lead to another fence post, the lag stopped for the most part, but occasionally happened again.
It was by pure chance I went to test destroying a block right as the Happy Ghast had moved close enough to the ground that it’s tentacles where obscured, that the game was laggy, and when it moved up again, no lag.
I tested it a few times more, and whenever it was close enough to the ground, it lagged.
So now it’s tied up high into the air away from solid blocks, and no more lag to report.

I assume something about the new entity interacting with solid blocks is the thign causing it, though without testing if more than just the bottom of the Happy Ghast interacting too closely is to blame, or perhaps the entire mob surface, that’s my best guess.

Attached is just a screen grab of my coordinate worksheet, with coordinate data, scatter graph, min/max coords, and approximate circle diameter.