Bingo ... it's that USB connection. Guaranteed that will b e ch o pp y to view.
Over on the Tweaker's Page (found on the hardware forum assets) they have a chart of sustained throughput for various internal and external drive connections & types. USB3 is much better than say USB2 ... but still not nearly fast enough in sustained read/write speeds for use in playback. Basically, for external drives, eSATA II or III or Thunderbolt are the only ones that can really carry the load.
neil
