"Limited retransmission"? If it didn't get there, eventually you have to retransmit it. QUIC allows re-transmitting somewhat fewer packets, because if you got packets 1,2,3,5,and 6, you can ask for packet 4 without getting 5 and 6 again. Whether this matters all that much in practice is not clear. Over bad mobile connections, maybe.<p>QUIC is a connection oriented protocol on top of a datagram protocol, just as TCP is, one level down. QUIC is on top of UDP so that it could be installed without cooperation from operating system vendors. That has more overhead than doing it over IP.<p>QUIC avoids head of line blocking on multiplexed streams, but is that a major problem? It might be for Google, which wants to feed as much content from Google as possible, rather than pulling content on a web page from multiple sites.<p>Are there stats from sources other than Google on QUIC performance over actual data paths? The original papers were entirely from Google.