Jake2 is a port of Quake2 written in Java. According to the benchmarks (http://www.bytonic.de/html/benchmarks.html), Jake2 performs approximately the same as Quake2, depending on the hardware.
http://www.bytonic.de/html/jake2.html
I have yet to try it, but I will, and I will post back here when I do.
It runs beautifully. I beat the Quake2 demo level. Go me! :)
A port, as in it's exactly like the original game, or a recreation? Either way, I'll definately have to check it out some time.
A port or recreation, I don't know. It feels exactly the same and uses the same level files. It's probably a port since Quake2 is opensource (now).
That's great, A+ to the developers.