Okay, so there's a problem that still plagues my city project on my Realm to this day, and I don't know what to do to fix the problem...

You see, back in 1.13, I was trying to do something with repeating command blocks to make plumbing by spawning in water buckets in that building shown in the attachment (located a short way west of the coordinates of X:-1000, Y:77, Z:-1000), but then a glitch happened, those repeating command blocks disappeared, and the frame rate in that place dropped dramatically as a result.

I cannot go anywhere near that building without experiencing lag so bad that if I stay in the area or try to approach the building, my Realm forces itself to be closed. Every other place on the map works fine and runs smoothly, except for this area here that I have talked about.

I don't want to have to use a backup, because of how long ago it has been since the incident first occurred, which would mean roughly 2 years of progress in my city project would be undone as a result. How should this issue be fixed?