As you requested, I created a local account under my administrator account, rebooted, and logged in as that local user. It did not have any affect on the download speed/bandwidth, either via wi-fi or over ethernet.
I still don't understand why my Surface Pro download is only half of my much older XPS's. I just got a new Linksys modem for my home today. XPS speed test results - 155 Mbps. Immediately then tested the MSP6 - same service provider, same wi-fi network, same band, same channel - 68 Mbps. Less than half...