which one is fit for image processing?CPU or GPU?

I write a fragment shader to do a image blur effect,but I found the shader let my program’s fps drop down.I do my test in a NVIDIA FX5900 card,I found the fragment shader performance of it is poor,so is it the time to let GPU to dome some image processing work?Compare to CPU,which one is more fit?

Eh? The fragment shader I assume ran on the GPU. Are you suggesting a third GPU option? Image blur effects have been implemented very efficiently by tapping a texture image with multiple coordinates in a fragment shader. That’s probably about as fast as it gets and way faster than the equivalent CPU program, especially when you consider readback and the parallelization of CPU and GPU.