This is a project that my co-worker Jon has been beavering away on in his spare (*cough*) time. I've been trying to help out with various performance things, such as finding more efficient ways to put the graphics on the screen.
Have a go. It's a fun project. Runs like treacle on anything but blazing hardware. But if you find the secret ingredients to make it go 2 or 4 times faster then I'm sure Jon will be most grateful.