"Yes, thats true. If Jumbo frames were supported end-to-end, slow start would start with a 3x9K = 27K congestion window and would grow the window by 9K at each increment. Instead, it has become common practice to use a much larger initial congestion window. Google has a proposal before the IETF to set ICW=10 (http://research.google.com/pub.... Microsoft has also experimented with a larger window. The congestion window still grows by only 1.5K per iteration, but at least it starts from a larger base." - DGentry