I'm not entirely sure if this would work, but it's an idea:
First, fork off a child that is able to change each players object. This process could check (e.g. periodically, once per second or so) that every player-object has the rooms around it loaded and deletes not used rooms again.
Now the main programm should be able to go in whatever direction is allowed (by the room the player is currently in) and just "go" there without having to load anything. Now you could send a signal to the child (or have it check after some time, or both) and the child loads the nine new rooms and forgets the old nine. Then all you'd need is a 9x9x9 array for each player. And if you use only six directions (up, down, right, left, forward, backward) you can use an even smaller array.

That's the idea.. Hope it was of any help ;)
-octo-
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