The OpenGL renderer is a pretty CPU-intensive one. I also get the same kind of framerates with my Duron 1 GHZ + GeForce2 MX. That's the reason why I introduced the precision parameter (F2 key) which allow to increase the framerate by reducing the amount of polygons computed.

The OpenGL renderer computes for each frame the whole polygonset using the marching cubes algorithm. Considering the geometry, this involves a lot of polygons.

To really boost the whole OpenGL process, it would be possible to use some display lists: but the performance would only be good with static geometry (which I'm really not looking for).

Anyway, if someone have some optimization ideas, please let me know !
Emmanuel.