Sadly a lot of us still rely on single thread style downloads. Currently I am trying to download VS2017 (offline) for installation at work (where we can't download stuff). I find it curious that VF demand speed tests from speedtest.net and no where else when they have performance complaints. The speedtest part of the VF app on my phone offered up 30Mbps up and down the other day (on my 80/20 service), so it obviously can't be trusted!!
3hrs in, and I've got about 20GB (or what I am expecting will be about a 45GB download.... and it am sure it is only going to get slower as the evening progresses.