It's easy to make the mistake of assuming your application bandwidth is directly related to your WAN bandwidth. Most applications rely on TCP as an underlying transport mechanism, which is constrained by a window buffer. Most modern systems have a 65Kbyte window, which means only 65Kbytes of data can be in transit across the WAN before receiving an acknowledgment from the recipient host.
If your WAN latency is 100 millisecond, you could only have 65Kbytes of data in flight before the next acknowledgment. Another way to put this would be to say that you would only be able to achieve 81,250 bits/second!
