The download speed depends even from the network/Internet bandwidth.
On the device is a 100 Mbit/s network interface, but the realistic maximum download speed is approx 22 Mbit/s.
This data must be also written to the USB stick or µSD card which take a bit time.
That´s means if there is no bandwidth limitation then the download of 1 GByte of data will require below 7 minutes.
In the LOG files of the Exstreamer Store&Play you can find information about the speed for the downloaded files.