I don't really have an issue with this but am genuinely interested in what the answer might be...
Say I go into photoshop and have an image, go to Filter then Filter Gallery.
Clicking through the filters it takes maybe 0.2 seconds to load some of them completely. This adds up if I want to apply a filter to an entire video.
Yet, I can render a 3D scene in OpenGL in real-time with some post processing effects to choose from, and when I flick through them the entire thing is rendered instantaneously (0.0079s to be precise, just 0.0001s more than a frame without an effect).
So I was wondering... Does Photoshop not use the GPU to apply these filter effects? Do the filters have to be compiled each time you select them? Is it just that CS6 is now considered old and poorly optimised?
My final theory is that some effects cannot use the GPU because they use a certain algorithm (particularly the palette knife effect) that specifically needs to look at the pixels in order - that wouldn't work in parallel.