Only Problem: Total compile time of this map was about 3 hours
Did you remove invisible cubes? You could write a simple function to remove any cube, that cant be visible from the outside. Just itterate over all cubes, and mark those invisible, wich have a solid cube on all 6 sides. This cuts down the number ob cubes by 80% on average. (you probably want to do this before exporting the data to wmb)
Also check that the cubes are exactly on non floatingpoint positions, this should help the buildprocess a lot.