I found this solution that worked for me, you have to go first to the task manager and search for "service host: network service", then select "Delivery optimization" and stop the process (or stop it from the services tab). It will automaticaly recover your download speed, I dont really know if this service actually affects anything else, so i do not recommend stoping it permanently, just during your downloads.
If someone knows more about the subject, I need you to explain it more thoroughly so I don't cause any problems with your systems. Hope it helps