I think the downloading estimates are done by the browser itself, not by Windows.
I have noticed that when downloading large files that the math shown ( amount downloaded, time remaining) is overly optimistic.
As I was downloading a 184MB file, 15 minutes after the download started 95 MB had been downloaded and the estimate of time remaining was 2:38. The actual amount of time it took was another 20 minutes.
I'm using Firefox but I'm assuming these computations and data are coming from a windows 10 API.
I'm using windows 10 home version 1511, build 10586.420.
Thanks


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