To turn off the advanced networking features like EnableRSS (Receive Side Scalling) and/or TCPChimney which can be somehow slow you setup very much down to the speed of a turttle:
Press Shift & F10 during first setup wizard page on every box:
netsh int tcp show global
netsh int tcp set global chimney=disabled
netsh int tcp set global rss=disabled
netsh int tcp show global