So to be clear, here are the tests you have run: TCP, throttled (1300kB/s limit ?) uTP, unthrottled I could also use results for: TCP, unthrottled uTP, throttled (1300kB/s limit ?) The current theory is that your router does not have a significant buffer - this would explain the inability to affect ping times while uploading unthrottled. So instead of delaying a packet, it would simply drop it. Packets that make it through have no extra significant delay. In this case I believe uTP will perform no worse that TCP, but basically the same. Your tests will prove that one way or the other.