Copy file(s) from Windows 2008 to Windows 2003 client, over file share, poor performance

The solution was to turn off all offloading in the Virtual Network adapter. I disabled the following for both ipv4 and ipv6:

  • IPv4 Checksum Offload
  • Large Send Offload Version 2
  • TCP Checksum Offload
  • UDP Checksum Offload

The virtual adapter has various types of offloading enabled, which can cause a problem if the physical adapter is not server grade hardware.