The Issue:

For the curious among you, this issue is caused by the new network throttling code Microsoft first introduced into its operating system with Windows Vista SP1. Because multimedia programs require more resources, the Windows networking stack implements a throttling mechanism to restrict the processing of non-multimedia network traffic to 10 packets per millisecond.

In circumstances where you experience a decrease in network performance, you can control the throttling rate to improve network performance in Windows.

To configure the throttling rate, change the value of the NetworkThrottlingIndex registry entry under the following registry subkey:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\NetworkThrottlingIndex

The fix:

1. Click on Start » Run » Enter regedit and click OK.(screenshot)
2. Navigate to the following location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile\
3. The registry is very similar to your file system (Think of My Documents). There are folders, and within those folders are files (called Keys).
Double click on the NetworkThrottlingIndex (DWORD) key, and change its value to FFFFFFFF (hexadecimal).
4. Reboot your computer.

WARNING!
Putting the wrong values in Windows registry might crash your system and lead to lots of problems. It is always recommended to back up your Registry before editing it. On info how to back up your registry:
Windows XP:
http://support.microsoft.com/kb/322756
Windows 7:
http://windows.microso…ows7/Back-up-the-registry
Windows Vista:
http://windows.microso…ista/Back-up-the-registry