As discussed previously, we're going to enable RFC 1323 Window Scaling and increase the default TCP receive and send windows to 1 MB. By default Windows 2000 and XP do not offer window scaling options, but will accept them if offered by the other side. To make our changes, we'll need to modify the following registry keys under HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters and reboot the system.

Tcp1323Opts = 3
TcpWindowSize = 1048576
GlobalMaxTcpWindowSize = 16777216

Using Registry Editor to Update Windows TCP/IP SettingsYou can edit the Windows registry with Registry Editor. To start Registry Editor issue regedit at the command prompt or in the Run box. In this image, you can see the various options being set. Remember to select the radio option for Decimal, otherwise your values won't mean what they should.