Update on the GPU benchmarking:
I forgot to mention that we do have samples for testing the speed of CUDA processing at OptiSystem 13 Samples -> OptiSystem performance -> CUDA examples. Although without a graphics card that specializes in scientific computing, you will probably experience 5 to 6 times increase in performance.
Currently I am arranging for a test with the NVIDIA Tesla K40 and if all goes well we should have a good benchmark for what is possible with CUDA.
Cheers