For anyone downloading the warzone update use this free VPN - betternet (I went from 800kb download speed to 4.5mb!!)
Maybe you just have bad internet.
Although I would not recommend this, there may be situations in which using a VPN can help. For example, if the local mirror of blizzard has only little bandwidth left you can use a VPN to switch the mirror server (if there is no option in the battle.net client itself. Usually, the mirror is chosen by geoip location)
However, just waiting a bit would help without getting another company to spy on your internet traffic…
That is fine I guess