I don't spend much time on Windows machines but fast previews accelerated by the CPU are very quick in CS6 even without an NVIDIA card. AE still isn't instantaneous but it's way faster if you have a modern system and plenty of memory.
The term Fast Preview is not as specific as you are indicating in your post. There are many preview modes in After Effects under the Fast Previews heading. Some are OpenGL-accelerated; some are CUDA-accelerated; some are CPU-only.
The GPU is used for very little in After Effects. The only thing that you really need to think of regarding the GPU is CUDA processing for the ray-traced 3D renderer in Final Quality and Draft modes. OpenGL is used for the Fast Draft mode. OpenGL is used for a few other things, too, but not in a way that should make you need to consider buying an expensive/powerful graphics card for it.
See this page for details:
Can I piggyback on this question?
Just your opinion if you have time to respond. On a scale of 1-10 - ten being best - what kind of performance would you think I should be getting with this scenario
- i7 950 3.07GHz - 12GB ram - NVidia GTX 670 4 GB - Windows 7 64 bit - 80GB SSD media cache drive. - System and AE on an SSD - Footage and assest on internal SATA and Externa eSata?
Ram reserved for other apps 4GB
Render multiple - 3 reserved - RAM allocation per CPU 2GB
I'm not complaining but wonder if it's normal to need to work in draft and at less than full rez often - particularly with ray trace - but with partical world and some other simulation fx. Also, not fully grasping the Cache Work Area in BG feature. Is that in addition to a ram preview? Can you run that simultaneous to your ram preview? Watched some tuts but I must be dense. Just don't get it. Also, does the app decide it it's going to use your cuda gpu or open gl or do I need to flick a switch or something?
Tia if you get the time and see this.