To my knowledge, MCHPRS is not a full Minecraft server implementation; it only contains just enough subset of the game to run redstone circuits. The upside is that this subset can be run a lot faster than the full game server.
The rest of the game remains unimplemented not because it couldn't be done, but just because it's a lot of work. World generation, mob logic, all the different crafting recipes, world generation, etc wouldn't impact the performance of the redstone system, but it's not necessary for the use-case of running CPUs fast.
