HTTP/2 vs HTTP/3 Latency Modeler
HTTP/2 vs HTTP/3 Latency Modeler
Model RTT, head-of-line blocking, and packet-loss effects on TCP vs QUIC throughput and page-load time.
Loss Rate vs Page Load Time
Protocol Comparison Reference
| Feature | HTTP/2 (TCP) | HTTP/3 (QUIC) |
|---|---|---|
| Transport | TCP (reliable, ordered) | UDP + QUIC (reliable, stream-independent) |
| Head-of-Line Blocking | Transport-level HoL on TCP loss | No HoL — lost packet only blocks one stream |
| Connection Setup | 1-2 RTT (TLS 1.3) | 0-1 RTT (0-RTT resumption) |
| Multiplexing | Multiple streams, TCP HoL | True parallel streams, no HoL |
| Loss Recovery | TCP retransmit blocks all streams | Per-stream recovery, others continue |
| Best on | Low-loss LAN / datacenter | High-loss mobile / lossy WAN |