Netsh int tcp set global autotuninglevel=disabled

To see the current configuration for the autoTuningLevel parameter: netsh interface tcp show global
The value for the autoTuningLevel parameter is listed as Receive Window Auto-Tuning Level. The following list includes all possible values for the autoTuningLevel parameter:

disabled - Sets the receive window at the default value.
highlyrestricted - Lets the receive window grow beyond the default value, but does so very conservatively.
restricted - Lets the receive window grow beyond the default value, but limits such growth in some scenarios.
normal - Lets the receive window grow to accommodate most scenarios.
experimental - Lets the receive window grow to accommodate extreme scenarios.

Note The experimental value may decrease performance in common scenarios. This value should be used only for research purposes. The TCP receive window size is the maximum amount of received data in bytes that can be buffered at the same time on the receiving side of a connection. The sending host can send only that amount of data before waiting for an acknowledgement and for a "receive window" update from the receiving host.

The TCP/IP stack in Windows Vista tunes itself in most environments by using larger default window sizes than in earlier versions of Windows. Instead of using a hard-coded default receive window size, TCP automatically adjusts the window size to increase the percentage of full-sized TCP segments that are used during bulk data transmission. This helps limit the number of segments that are sent when large sets of data are transmitted.

When auto-tuning is enabled in Windows Vista, Receive the Window Auto-Tuning feature continually determines the optimal true receive window size by measuring the bandwidth delay product and the application retrieve rate. Then, Receive Window Auto-Tuning adjusts the maximum receive window size based on the changing network conditions.