tingnan mo rin kung meron ibang nakalagay na USB devices
kasi ang speed ng USB 2.0 is 60MB/s (max), PERO per controller yan. so example, yung nasa front side ng case mo pag may dalawa dun, those will only use one controller so those two combined 60MB/s and max speed na pwede (although depende rin sa flash drive mo kung ano lang kaya). so if you have another USB device connected, that could be the reason kung bakit bumagal ang transfer speed.