I was really surpised to see the results from this video, and have to wonder if there have been some recent changes to the MadMax plotter that have led us to a point where we are seeing better multi-threaded handling as you scale the core count. The T620 used for this is a dual socket processor, so these measurements are for dual sockets.

E5-2667v2 - 8c/16t 3.3GHz base frequency - 31:10 per plot
E5-2637v2 - 4c/8t 3.5GHz base frequency - 51:00 per plot

This 20 minuite difference is hard to believe as these both were running on a 110Gb ramdisk for the -2 and using a 8 x 1TB Samsung EVO SSD Raid0 array for the -t directory.