(Source: http://social.answers.microsoft.com)

Disable Remote Differential Compression

• Click Start – Control Panel – Programs – Turn Windows features on or off
• Uncheck Remote Differential Compression and click OK
• Restart the computer and you should see an improved performance with copying files.

Disable TCP AutoTuning and Receive Side Scaling

• Open an elevated command prompt with administrator rights.
• Type the following commands and press Enter (the second command on RSS is optional):

netsh interface tcp set global autotuninglevel=disabled
netsh interface tcp set global rss=disabled

Reboot the computer