It looks like the opposite to me? TCP minimum header is 20 bytes.[1] QUIC "short header" (after key negotiation) looks like it can go down to 2 bytes for non-r

It looks like the opposite to me? TCP minimum header is 20 bytes.[1] QUIC "short header" (after key negotiation) looks like it can go down to 2 bytes for non-roaming connections with a 1-byte packet number, if the server allows the omit_connection_id, and 10 bytes otherwise.[2] Add the UDP header (8 bytes[3]) and you're at 10-21 bytes. So if you both supply a connection ID and a 4-byte packet number you're just barely at the same transport overhead as TCP; otherwise it's less. (The QUIC "long header" is longer but that's a fixed cost and shouldn't matter too much for overhead.) Or am I missing something? [1]: https://en.wikipedia.org/wiki/Transmission_Control_Protocol#TCP_segment_structure https://en.wikipedia.org/wiki/Transmission_Control_Protocol#... [2]: https://tools.ietf.org/html/draft-ietf-quic-transport-08#section-5.2 https://tools.ietf.org/html/draft-ietf-quic-transport-08#sec... [3]: https://en.wikipedia.org/wiki/User_Datagram_Protocol#Packet_structure https://en.wikipedia.org/wiki/User_Datagram_Protocol#Packet_...