This post does not apply to most people, but if you have high speed Internet – it might. My daily driver is a 300 Mbps fiber line. It is fast and I can saturate the link but it takes multiple connections to do it (quite a few connections actually).
If I download a file single file via the web or FTP I might get 30 Mbps per second. That is fairly quick but it is a lot less than 300.
If I download two files at once, from the same remote server both files will come down at 30 Mbps for a combined speed of 60 Mbps.
If you are in the same situation, the problem is probably related to your TCP receive window. The TCP window combined with the distance in MS you are away from the source server determines your maximum download speed.
I found a great article that someone wrote that explains both the calculations of your maximum download speed potential – AND how Windows may actually be limiting your download speed. Yes, it is true!
After reading the article, titled How Windows is Killing Internet Download Speeds I learned that indeed Windows was limiting my connection speed.
I saw major speed increases when downloading from a server that was far away from me. Why Windows limits your connection speed is unknown to me, but simply by executing this:
netsh interface tcp set heuristics disabled
I was able to remove the limit and now download at full speeds.