OK well my ignorance is shining through. I'm not talking about anything complicated like messing with the actual file system itself (its ext2 BTW). Just that I know that in general when you are creating, say lots of virtual server doc roots or virtual maildirs, etc, you often "hash" them out (if hash is the correct term to use in this context) using a crude method.
Add another level to the hashing:
So, there must be some rule of thumb or algorithm that ppl use here to decide to what level of hashing out of directories produces the optimal balanced tree strucure in the file system.