JOIN US!! persons who hate JAVA!!

Seriously though, you gotta be into S&M if you decide to develop something in Java yourself and you'll be doing part of the job.

Well, most games spend the majority of their time in the draw-loop.  Any overhead incurred by the AI/networking is minimal.

Its like coding in C and ASM.  If you code a whole game in ASM, its fast.  If you code a game in C, but use ASM for the graphics code, its still fast.  You only take like 2% speed hit for your sins.  Its not quite the same with java, but the speed hit you take for using java with openGL API is still minimal.