There is definitely something very broken in the gov't version of the speedtest.net application. It seems very BW constrained. I can get great results to a variety of ookla sites via test points across the US, but the government one is always horrible.
We host both a pingtest and speedtest.net site, and provided you give it enough BW, it's reasonably accurate for connections up to around 50 Mbps.. Peter Kranz