Windows Vista controls your network bandwidth when you are playing movies such as MP3s or videos. This was aimed to increase performance when you are playing a multimedia file. But your network speed while transfers files will decrease on high speed network connections.
This is caused by playing a multimedia file your network transfers are limited to 10 packets per millisecond.
In Windows Vista SP1 Microsoft introduces a registry key that allows you to customize this setting.
- [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile]
- NetworkThrottlingIndexValue
You can set NetworkThrottlingIndexValue between 1 and 70. If you want to disable change the hexadecimal value to FFFFFFFF.
Microsoft warns that if you increase the value above 10 you may experience playback quality issues.This is not a final verdict. Do some experimentation to settle for a final value.
After making any changes a restart is needed.
Read more about this tweak on KB948066