I think you should try to do some experiments with straight ray marching, just for comparison. In my tests, I got nicely convergent renders with a 970 + Vive @ ~1.2ms GPU time, and some overhead for rendering the cloud shell into custom depth (.3-.4ms). There isn’t much CPU overhead. This is with 25 samples per ray and my dense clouds with a 3d texture that is 950x950x600. If you weren’t running in VR, or didn’t have a massive amount of other stuff going on like we did, you could really bump up the sample count, and add a ton more complexity.