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.

RTT (ms)

Packet Loss Rate (%)

Bandwidth (Mbps)

Number of HTTP Streams

Page Size (KB)

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