When I undo changes, it's taking much longer than usual (what would take a fraction of a second, now takes up to 3~5 seconds at least, and is very laggy).

In many occasions, after you undo more changes, previously undone changes suddenly pop back, as if they were never undone to begin with.

I noticed that when you export the map, it's also glitchy, sometimes undone changes appear, sometimes they do not.

Recovering usually fix this issue, but this is happening very often, and constantly recovering is not a desirable task.