Q: Why is there a performance problem between my Windows XP virtual machine running in Windows Virtual PC and my host computer?

A: Problems can be caused by your physical NIC using TCP offloading, and the emulated NIC within the virtual machine (VM) Intel 21140 not supporting TCP offloading. To address the performance problem between the VM and the guest, you have several options.

If you have multiple NICs in your desktop, you can disable TCP on the second NIC and use that NIC for the VMs. Another option is to disable TCP offloading on your system.

To do so, navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetservicesTcpipParameters in the registry and create a DWORD value named DisableTaskOffload. Set it to a value of 1, then reboot.

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