It is also affected if there are top stairs above.
I think this is still an issue. At least in singleplayer. Saving worlds in 1.16.5 (and 1.17 snapshots) always takes minutes, but in 1.15.2 it took less than a second for me. I think this should be reopened.
2020-07-22, 05:27:40 PM UTC
MC-195788
It is also affected if there are top stairs above.
I think this is still an issue. At least in singleplayer. Saving worlds in 1.16.5 (and 1.17 snapshots) always takes minutes, but in 1.15.2 it took less than a second for me. I think this should be reopened.