GPU performance for fast hologram reconstruction issues!!

I have an NVIDIA Quadro K2000 driver installed, specifically for a better speed performance for hologram reconstruction using Octopus program. It doesn’t look like the GPU increases the performance speed at all (at least I couldn’t tell the difference). Is there any way to detect if the program is utilizing the GPU to reconstruct the holograms or not?

I am not familiar with the Octopus program. Is there a forum dedicated to this application where you could inquire about how to check whether GPU support is turned on? Even if it runs GPU-enabled, you probably should expect only moderate speedups, especially if you have a fast CPU in your system, since the K2000 is a fairly low-end device as far the Quadro line is concerned. According to this overview from NVIDIA

the K2000 seems to provide 64 GB/sec of theoretical bandwidth and 623 single-precision GFLOPS. Best I can figure out, the double-precision performance would be 26 GFLOPS, since the K2000 is based on GK107 which provides double precision at 1/24 of the single precision rate.