DCC does not work in the traditional way of tcp transfers. It receives a chunk of data, then responds to the sender, and the sender continues with the next chunk. Some clients will not even send more than the first packet, a couple of Kbytes, unless they receive the proper response from the recepient during a DCC (other less-conformed clients just dump it like any other tcp xfer). Really I don't know any reason why mIRC couldn't have a threshhold on incoming transfers, it's just not there (yet). I could be wrong though.