Windows 10 Uses Your Bandwidth to Distribute Updates, Disable It Here
 

This new distribution method works a lot like torrents do. Everyone has Windows 10 on their machine, so each person seeds a little bit of the files to those who need it, distributing the load across multiple computers and helping everyone download updates quickly. This is a great feature for those who have no data cap and want fast updates. The problem is, many ISPs have some form of data cap. This can potentially use up your allotment of data without you even realizing it’s happened.

http://lifehacker.com/windows-10-use...ifehacke r%29