HTTP/3 is faster with some work and help from Cloudflare

Delivery Hero, the global food-delivery company being acquired by Uber, moved most of its mobile users to HTTP/3 to reduce delays across regions with uneven network quality. The protocol uses QUIC over UDP rather than HTTP/2’s TCP, enabling faster connection setup and allowing eligible data to be sent before a connection handshake finishes. Its separate data streams also avoid the head-of-line blocking that can stall HTTP/2 when packets are lost. Delivery Hero relied on Cloudflare’s network, so enabling HTTP/3 on the server side was straightforward; Apple devices and browsers largely supported it already.

Android required more tuning. Delivery Hero adopted Google’s Cronet networking library, but its roughly 800-millisecond startup time at the 90th percentile undermined HTTP/3’s speed gains. The team built a custom bridge and overlapped Cronet initialization with other background work. After these changes, P95 read latency fell from 1.2 seconds to 120 milliseconds, and the home screen’s end-to-end response time improved 17 percent. About 95 percent of users now use HTTP/3, with unsupported or UDP-blocking networks falling back to HTTP/2. Handshake latency dropped 51 percent, and response times in Pakistan were halved. Some secondary screens still lag in packet-loss-prone markets; Delivery Hero suspects Cloudflare’s Cubic congestion control and is working with the provider on a fix, after tests with BBR-based servers performed better.