Harvey,
15-17 min Normally with USB 2.0 a download like the takes less than 5 min.
Are you saying that when copying the files off the card via your USB 3 card reader with the Finder takes 15 to 17 minutes?
If so then I suggest contacting the manufacturer of the USB 3 card reader and asking them why it is so slow when it should be much faster than a USB 2.0 reader. Perhaps they have an updated driver?
If the read speed is slow for the Finder, it is going to be slow for Photo Mechanic as well. There would be no solution that could be engineered from our end.
-Kirk