How do HTTP/3 and the QUIC protocol differ?

12 Tem 17:23

One of the biggest advantages of QUIC being the foundation of HTTP/3 is the connection initiation time. Unlike TCP + TLS, which requires a handshake, QUIC completes it in a single round (0-RTT). When we tested HTTP/2 in a similar scenario, we were losing 200-300ms, but with HTTP/3, we reduced it to under 50ms. This translates to significant performance gains, especially on mobile devices or networks with high latency. QUIC also handles packet loss differently. Since it's built on UDP, it only resends the lost packet—not the entire connection. In TCP, even a single lost packet can trigger congestion control and instantly drop throughput by up to 30%. In our tests, we observed that recovery time after packet loss in HTTP/3 was on average 40% faster than in HTTP/2. Of course, they don’t compromise on security because TLS 1.3 covers UDP’s "unreliable" nature. On top of that, QUIC’s Connection Migration feature is really handy. When a mobile device switches from Wi-Fi to mobile data, you don’t have to reestablish the TCP connection—it just continues seamlessly. In a similar test, HTTP/2 took 2-3 seconds to reconnect, but with HTTP/3’s migration, we cut it down to under 300ms. That makes a huge difference in user experience.