Hysteria2 Deep Dive: Why It Is So Fast

At peak hours, when every TCP-based node crawls, Hysteria2 nodes often still run at full speed. The secret: it abandons TCP for UDP-based QUIC and adds unapologetically aggressive congestion control.

Where the speed comes from

• QUIC multiplexes streams over one handshake — lower latency to start with
• Its congestion control shrugs off packet loss instead of collapsing like TCP
• 0-RTT reconnects make WiFi-to-cellular handoffs nearly seamless

Good fit, bad fit

Great for lossy long-haul links, mobile networks, video and bulk traffic. Poor fit where carriers throttle UDP hard — with UDP QoS in force, TCP-family protocols can actually feel smoother.

Using it

Nothing to configure: if the subscription carries Hysteria2 nodes, every client on this site supports them via mihomo. If hy2 nodes are fast by day and crawl at night, that is UDP QoS — switch to Trojan or VLESS for the evening.