ConnectPort X4 Flash Drive slow transfer speed

I’m trying to do the following: download a small file (200KB) from the attached flash-drive on my ConnectPort X4. It is running a Python script based on the callback routine:

if path.startswith("/getFileFromUSB"):
                print "** Trying to send a file from the USB Flash drive"
                print time.clock()
                response = open("A/%s"%(path.split('/',2)[2]), 'rb').read()
                print time.clock()
                return (digiweb.TextPlain, response)

However, this means that every file that I read takes up some 3 seconds for barely 200KB of data. I see the same issue when downloading from the internal Flash memory (/FS/WEB/…)

Is this a setting somewhere, or is the hardware really limited to about 70 KB/second?

Note: using this in your digiweb callback makes every file on the USB drive potentially readable by anyone with access to the device.

A screenshot of the Net panel of FireBug with an example;