Wow that's a shame to hear. My PC isn't quite as powerful as yours but it handles voxels like warm butter, same on my laptop. I'm running a Core 2 Quad 2.4GHz 64 bit CPU, 6GB ram with an older 8800GTS card. Are you using the CUDA version? Your card should be compatible. If you're using the Direct X version try the Open GL one or vice-versa.
Well, I believe you were correct, it was because I was using too large of brushes. Using small brushes is very fluid and I don't have the problem mentioned earlier at all. I still would sort of expect a little better performance than what I get, but perhaps I don't fully realize what is happening with these voxels.
Anyways, I am using the 64 bit version, but not the CUDA 64 bit version. I tried to install CUDA a while back and shortly after my computer started getting blue screen errors. It might have simply been by coincidence and not had anything to do with CUDA at all. But I can't really risk it, since I make a living off my computer, and I need it working at all times.
My review on 3d Coat:
I still prefer using good old mudbox for my sculpts. Mainly because I believe that working with subdivisions is a bonus actually, as it lets you refine every sub-d more and more. And if done correctly actually gives you more control. However, I think Voxels are ideal for creating base meshes on which to sculpt, and general 3d concepting. Also, certain things that would be a huge pain to create hardsurface wise in 3ds max, would be ridiculously easy in 3d coat by just joining objects or using the booleans.
Plus, I really like the retopo tools, and I'm going to have to give em a go sometime to see if I prefer it over 3ds max 2010 tools. Painting wise, I prefer bodypaint for sure, I'm just used to it and it has everything I need. Mudbox is actually quite nice at times as well painting wise, because you can view your normals real time while you work.
But there are certainly enough things happening with 3d coat that I am convinced that it will help me out. I'll probably pickup a copy when my trial period runs out.