There are alot of articles on the net stating the following steps helps.

1. Click on Start then Run.
2. Type in gpedit.msc then click OK to launch the Local Group Policy Editor.
3. Select Computer Configuration > Administrative Templates > Network > QoS Packet Scheduler.
4. On the right panel, select Limit reservable bandwidth, right click and select Properties.
5. Select Enable and enter 0 (zero) in the Bandwidth limit (%) text box.
6. Click OK and exit Local Group Policy Editor.

Though the Limit reservable bandwidth is set to Not Configured, by default 20% is set to reserve a portion of the connection bandwidth for Windows update and stuff.

Honestly, I do not see how this will affect the internet speed especially when the PCs are connected to a network through wired (10/100 mbps) or wireless (11/22/54 mbps) medium. Windows will detect the respective local network connection speed rather than the actual outbound internet connection speed, since the internet connection will be connected to either the switch or a router. So after subtracting 20% off the LAN speed, it still shouldn’t affect the internet speed as the balance will still be greater that the actual internet connection speed.

So… for those who are desperate to speed up their internet connection, do give it a try and leave a comment here with your outcome.