Vista-kb9 Resolve slow Vista network performance
Difficult level: 3/5
Status: Tested and works, more scenarios and different solutions needed.
Microsoft Windows Vista has a new rewritten networking system with a lot of new features speeding up TCP/IP traffic. These new functions require that the hardware such as routers/switches and other servers supports it, QoS (Quality of Service).
In certain network environments these new features does the opposite and slow down your connection speed or doesn't work at all, one such feature is Receive Window Auto-Tuning that allows the system to feel the network speed and adjust the maximum receive window after the speed. (Windows XP and Windows server 2003 has a set value that can be changed in the registry, HKEY_LOCAL_MACHINE\System \CurrentControlSet\Services\Tcpip\Parameters\TCPWindowSize)
Disable Receive Window Auto-Tuning in Vista
If you encounter network performance with a Vista machine in a network with legacy operating systems and hardware try to disable Receive Window Auto-Tuning with the following command in an elevated cmd prompt:
netsh interface tcp set global autotuninglevel=disabled
netsh interface tcp set global autotuninglevel=normal
Disable receiver-side scaling
If the above doesn't fix your problem it could be worth testing to disable receiver-side scaling (rss) with the following command in an elevated cmd prompt:
netsh interface tcp set global rss=disabled