I realise this one really should not happen in a synthetic renderer, but it does. Although flames from Apophysis are tack-sharp, Flames from Flam4CUDA display a soft-focus effect and several pixels of camera-shake. This is not improved by increasing quality from 1,000 to 100,000. It just takes longer to generate the same blur.
Core2Duo T5250; 8400M GS; Vista; 3GB; drivers currently 195.62 though have tried others and it makes no difference; Flam4CUDA 0.81 & 0.83