50,000 steps of MD with "identical" settings, to the best of my ability. The
precision models used were "mixed" for the OpenMM CUDA platform and SPFP for
pmemd.cuda. The only printouts that were done were a single trajectory write.

            OpenMM                          pmemd.cuda
            ------                          ----------

      steps   | Total time (s)          steps   | Total time (s)
    --------------------------        --------------------------
      10,000  |   374.9797              10,000  |  86.58
       5,000  |   375.5790               5,000  |  85.89
       2,000  |   378.6431               2,000  |  85.96
       1,000  |   384.0025               1,000  |  85.93
         500  |   395.7065                 500  |  86.34
         250  |   417.7666                 250  |  86.31
         100  |   484.1631                 100  |  87.03
          50  |   597.1071                  50  |  88.20
          10  |  1478.6362                  10  |  98.74
           5  |  2677.9380*                  5  | 109.40*
           1  | 11431.2420*                  1  | 199.20*

* Extrapolated from 5000 steps