Slow Remote Desktop Connections on Vista and Windows 7

After I got my new, blazing fast Windows 7 workstation I started noticing that some, but not all, of my remote desktop connections were much slower than they were from my old, slow XP workstation.  The remote server would take a long time to respond to mouse clicks and key presses.  I suffered with this for a couple of months before I got fed up enough to start researching the problem.

It turns out that Remote Desktop 6.0, the version that ships with Vista and Windows 7, uses a new operating system feature that allows RDP to automatically tune the TCP/IP receive window size.  Theoretically this is supposed to improve network throughput but apparently Vista and Windows 7 have a problem on certain networks.  Not much of a surprise that a new Windows feature would have problems. :(
Anyway, disabling or restricting the auto tuning feature fixes the slow RDP connection problem.  To disable auto tuning completely, enter the following command on the workstation.  You will need to start an administrator mode command prompt first.

netsh interface tcp set global autotuninglevel=disabled

In some cases, simply restricting the auto tuning feature to a more conservative level might fix the problem.  To make the auto tuning feature more conservative, enter the following command on the workstation.

netsh interface tcp set global autotuninglevel=highlyrestricted

There is an excellent blog post that goes more deeply into the technical details here.

One Response to “Slow Remote Desktop Connections on Vista and Windows 7”

  1. Andy Says:

    Interesting problem and an even better solution. Great fix! When you get a chance you should check out our page on Facebook at http://www.facebook.com/windowscanada

    Andy
    Windows Canada Outreach

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