I personally believe that experimental evidence as of my own observation described in the readmore section at the top of the root node would suggest just the opposite, (which probably I didn't make clear enough to start with) but to be fair I didn't take times with a cronograph nor did I repeat the experiment in a controlled manner, thus ++ on faith: however I'm still fairly convinced that they somehow "interfered" to the point of getting ridicolously slow.

Incidentally, it all started with an usb key, but I didn't say anywhere that the use of the utility should be limited to usb keys...

Just to make sure about your experimental evidence: A second copy should slow down the first copy to about half speed, any further copy should further lessen the speed of any single copy to 1/n with n the number of copies. That is to be expected. But you have seen a speed reduction much higher than that?

In that case I stand corrected. Must be some hair brained implementation somewhere.

Indeed that was my impression: I had three transfers at a time, each of which seemingly processing much slower than at a speed of one third of a "regular one." But now you're making me having doubts!

--
If you can't understand the incipit, then please check the IPB Campaign.