Instead of working the way X does, the intent in Wayland is to do all rendering client side (the way things are done in practice under X these days anyway). Did you see the big thread on the mailing list about "Finishing the network protocol"?
> Sans the round tripping, which was the main point of this project.
The "main point" of Wayland has nothing to do with eliminating the (trivial) overhead of network transparency; rather, it's to finally get rid of all the legacy cruft that's accumulated in the X11 protocol over the years.
Much of X11, such as fonts, graphics primitives, and color palettes, is completely unused by modern clients (even remote ones) -- it makes sense to simplify the protocol by dropping such legacy features.
