Take the external drives out of the USB 2 enclosure (max speed 35MB/s) and move them into a USB 3 enclosure (max speed 400MB/s). You can also directly attach the drives to a PC via an IDE or SATA interface. The USB 3, IDE or SATA interfaces are going to allow you to run the drive at whatever the drive's speed is, rather than be limited by the transfer speed of the interface.