1.50068 bf/s (back-and-forth per second)
Last night I wrote a two HTTP bouncers, one on phoenix and another one on alseyn.net, and measured that in average, and including PHP processing (*), HTTP requests travel at 11.69% of the speed of light between London and La Habra (California, US). The timing showed a slight increase when the US went to bed...
In one of the timings, the object travelled 15346 times in about 5113 seconds, and died at midnight when BT reset our IP address.
(*) On phoenix, there was a base64 decode/encode and json decode/encode at each loop, to update the json object that was being bounced.