At P99 CONF 2026, Delivery Hero staff engineer Elvis Chidera explained how the company moved most of its 60 million users to HTTP/3. The Register has the writeup.
What they learned
- QUIC over UDP plus 0-RTT session resumption cut handshake latency 51%, and home-screen response time dropped 17%. In Pakistan it was cut in half.
- About 95% of users moved over. Networks that block UDP fall back to HTTP/2 automatically.
- On Android, Google’s Cronet library took about 800 ms to start at P90, eating into the gains, so they forked it.
- In markets with lots of packet loss, Cloudflare’s Cubic congestion control struggled. Google servers using BBR didn’t, and Delivery Hero is working with Cloudflare on it.
My take
HTTP/3 is worth it, but it isn’t a checkbox. Measure your startup costs, keep the HTTP/2 fallback, and pay attention to congestion control on lossy networks. Also, check that your firewall actually allows UDP 443. A lot of “HTTP/3 doesn’t work” is just that.
God Bless, and Use the Source!
