Most people are unaware that Windows limits your bandwidth by up to 80% of your computer’s network speed. While this may be fine if your PC is directly connected to your internet router or modem (as the 80% limit is recommended for outgoing and incoming traffic shaping), its not always wanted in a networked environment.
Lets say that you are transferring a file over your network from one PC to another. If that file is massive, you want it to transfer as fast as it can. Well, if Windows is limiting your bandwidth by up to 80%, then that can slow things down.
Here is a simple way of disabling QOS Packet Scheduler, which is the Windows compnent responsible for the limitation settting, via GPO.