4 more fps! ... well on average anyway :) So its now running at 25-30 continually. Last night did a small update to optimize the number of threads. Also added more colours to the spheres - and you can now press 'R' to get some very primitive physics (bouncing)
The download link is the same as the previous post but inside the zip is a version 0.02.
This is still without my new acceleration structures. They are taking a while to implement so as to maximize the efficiency in the way the GPU wants to read the memory. I'm hoping for at least a 2x speed up.