I was looking at this.
I then created a 400x400x400 map.
It took about a 1.5g of memory, and saving it took a while.
I then restarted dm, and opened the map file.
The memory went up to where it was before, then crashed.
Compiling it also causes a crash.
Instead of having the entire map in memory, Why not limit the loading of the map into memory some way?
Maybe, by only loading the Z above and below the current one?
Would anybody support having the option of making the map file independent of the dmb? It seems to be somewhat responsible for long compile times.