currently passive proxies are polled for data every second (by default)
might be useful to implement some scaling, similar to what several internal processes use. for example, if there is any data received from the proxy, server connects in one second. if not, it backs off to 2, 3, 4, 5... seconds.
this could be a multiplier of the set interval, or maybe parameter would accept a range (1-5, for example)