Horrendous downloads

Downloads take absolute ages. Everything from game installations, to game updates, to updates to the app itself. It will sit on “Initializing…” forever, until eventually transitioning to a bogus download display that sits at whatever KB out of whatever MB without budging until it randomly decides it’s done, which doesn’t seem to happen without some form of assistance.

My download speed is 40MB, so an update of 500MB should take no time at all, yet it takes up to 30 minutes just to get from “Initializing…” to downloading at what feels like 10KB/ps.
Closing, opening, closing, and then opening the battle.net app seems to fix this? What gives?