An early (1990) complaint about Java was its speed. A complaint totally unfounded with current releases as proved by Jake 2, an implementation of the Quake2 game engine in Java.

The code builds over the top of the Light Weight Java Graphics Library which in turn overlays OpenGL, the download installs easily (you will need a working Java Virtual Machine installed). I was interested in this to see how such a game could be coded and how the lwjgl is used and performs. Overall: impressed and reassured me about using Java and LWJGL in future games programming.