I don't know Visio but what I can suggest is that you could use 168.12 driver. I have 8800 GTS 512 and it's working 33% better on this driver. I don't have any problem with performance on Witcher and other games but it might be configuration ( e8400 3GHz 8800GTS512, 4GB RAM, Raptor 150GB ). I think I found a patch for better memory allocation but haven't tried yet. I will do it after weekend and share here with results.
