Can take many minutes to release memory / shut down

Test case was compressing a room which used a total of 87gb of memory. After it checked that the state maps match, it took about 5 minutes to release memory while also spinning a single core on the machine. During this time, the memory usage was slowly going down. Surely it should be able to just exit normally and release all the memory back in one shot?

No file, test, or entry point is named. Reproduce compression of a room using about 87 GB of memory, then investigate the shutdown and memory-release path while observing CPU and memory usage. Done means the tool exits without taking several minutes to release memory.

Written by the indexing model from the issue text.