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Workaround for Windows VPC networking slowness between host and guest

    General discussion

  • Hello,

    I figured out a way to speed up networking between the host and guest when using Windows Virtual PC, so this might help any of you if you've had the same problem.

    This slows your PC down a bit if you are pushing the networking, but turning
    off TCP offloading cures to slowness of networking between the host and guest in the VM.


    The fix is to edit the registry, use at your own risk and only if you are comfortable with editing the registry!

    To turn off TCP Offloading, add a DWORD value in

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\Tcpip\Parameters

    label it  DisableTaskOffload , and change the value to 1, then reboot.



    Bob Comer - Microsoft MVP Virtual Machine
    Friday, March 05, 2010 5:53 PM

All replies

  • Thanks Bob!

    Good 'ole TCP Task Offloading strikes again......
    You would think that a problem that has been around for so long would have been dealt with by now.  But then I have heard many folks at MSFT claim that this should not have to be done.

    However, I also know many folks that swear by turning this off (me being one) and have been for many years simply as a community best practice.
    Brian Ehlert (hopefully you have found this useful)
    Friday, March 05, 2010 6:57 PM
  • >Good 'ole TCP Task Offloading strikes again......
    >You would think that a problem that has been around for so long would have been dealt
    >with by now.  But then I have heard many folks at MSFT claim that this should not have
    >to be done.

    It must be something to do with the filter driver and the task offloading fighting each other from the way it acts.  No clue what really goes on though.
     
    >However, I also know many folks that swear by turning this off (me being one) and have
    >been for many years simply as a community best practice.
     
    I may have to do the same again. <g>   It's been awhile since I thought about it.

    As an aside, using a dedicated NIC for the VM's also gets the networking speed up to normal...
     
     

    Bob Comer - Microsoft MVP Virtual Machine
    Friday, March 05, 2010 7:05 PM