You would think loading 9 levels every time you stepped into one would cause even more lag.. ya know?
I mean think about it like this, you connect to the server, appear in a level, and it proceeds to preload 9 other levels around you.. you walk 2 levels over, and you're downloading another 9 levels. Maybe for gmaps it's okay.. but to have it do that with normal .nw levels would be bad I would imagine.