If you have an approved Graphics Card it will greatly increase the speed and pleasure level when working with the new Raytrace Renderer in CS6.
One other excellent new feature of CS6 is the ability to cache your current work are in the background. Rendering with Multiprocessing also continues to be improved in CS6.
However, any background rendering, such as the new BG caching, multiprocess rendering, terminal rendering, etc, are not currently compatible with CUDA Raytracing. If you are using the raytracer you must be filling your cache or rendering from within the app.
There is a workaround for those that have a render farm with compatible graphics cards, or wish to be daring and want to enable GPU rendering in the background. This is a workaround because it is not yet officially supported
1. Open Debug Database.txt in application pref folder.
2. Search for RayTracerGpuDisabledForHeadless in the file. Default value of this flag is true. Set it to false to use GPU Picasso renderer in headless AE.