HDD buffers tend to get full when larger files are being copied, so the transfer rate declines to about 1/4th of the normal speed because the buffer fills up faster than it empties creating a bottleneck. The time lost while the buffer is emptied and filled can be reduced and the transfer process can be faster if the copy process pauses for about 30 seconds (creating space in the buffers while they are being emptied, flushing data on the disk and there is no input into them). From my experience every 10 GB or so depending on the Hard disk cache size, a 30 second pause is needed for the buffers to resume normal transfer rate again. It would be great if we had the option to automatically Pause every xx MBytes for xx seconds. The gains are not the 3/4 of the lost time remaining, but rather half of it, but the transfers finish faster than the Windows default method.
The mentioned feature is included in Fileboss, Actions, More Copy Actions, Time Controlled Copy, to get the idea.