a) Ability when switching stacks to have one stack query another.
b) Internal use of micro-second timers instead of ticks.
c) Many changes to pacing in forms of
   1) Improvements to Dynamic Goodput Pacing (DGP)
   2) Improvements to fixed rate paciing
   3) A new feature called hybrid pacing where the requestor can
      get a combination of DGP and fixed rate pacing with deadlines
      for delivery that can dynamically speed things up.
d) All kinds of bugs found during extensive testing and use of the
   rack stack for streaming video and in fact all data transferred
   by NF