Fast handshakes

QUIC offers both 0-RTT and 1-RTT connection setups, meaning that at best QUICneeds no extra round-trips at all when setting up a new connection. The fasterof those two, the 0-RTT handshake, only works if there has been a previousconnection established to a host and a secret from that connection has beencached.

Early data

QUIC allows a client to include data already in the 0-RTT handshake. Thisfeature allows a client to deliver data to the peer as fast as it possiblycan, and that then of course allows the server to respond and send data backeven sooner.