Can't you use something better then java? Java is slow on 3D stuff and does not work will with PC
's with slow processors. Use C++ with OpenGL, A game like this using OpenGL programmed with C++ will give more fps and better performance. Java is very slow and sluggish. Make it on C++ OpenGL so it can run on old computers without a problem. OpenGL is better then DX3D because it can work on any OS.
Cypher100, what you want is a lot harder than it looks. The code would have to be entirely rewritten, clientside AND serverside. This'd take a lot of hours for Notch, taking valuable time away he could use to improve the current code and add new things. You don't want that right?
Besides, Notch is going to work on a stand-alone client later, which will make the game compatible with a lot more pc's.