hey guys,
i had the exact same problem, but i found a post which resolved my issues (almost) completly.
i'm running a HP dock with DL-3000 series on a samsung notebook.
The Notebook uses the Intel eXtensibile USB host controller.
i found more guys having performance issues using this controller under win8 with usb 3 external drives etc.
so i finally found this tutorial on how to install the original driver from intel (for win7) in windows 8. for me it solves the performance issues!
this is the link, hope it helps
http://plugable.com/2012/12/01/windo...st-controllers
greetz