[jakevoytko]

For simple testing purposes, it is easy to set up a forwarding proxy that drops n% of the packets it receives - for some high value of n. The World Wide Web is far more sadistic, but it still uncovers some performance or usability problems that are invisible over normal `localhost` traffic. I bet you can also use web servers with traffic shaping to mimic lots of slow connections at once, but I haven't tried that