According to the specs it is a 1000 Mbit/s interface - have you installed all firmware / driver updates? If I remember correctly, there was also a firmware update for the monitor itself. The quality of the USB cable could also play a role. I have a few of these monitors in use but I'm not sitting in front of them right now to verify the actual speed.

Have you connected an additional data transfer cable ? with this I then have a data transfer rate of 200-300 Mbit/s, it concerns the second USB with orange cover!