Optimizing Global App Performance with HTTP/3 and QUIC
Delivery Hero achieves significant latency reductions by migrating its global delivery infrastructure to HTTP/3.
1Latency Reduction via HTTP/3
Delivery Hero successfully migrated most of its global user base to HTTP/3, resulting in a 17 percent reduction in home screen end-to-end response times. By replacing the TCP-based HTTP/2 with the QUIC protocol, the engineering team effectively minimized the round trips required to establish secure connections on diverse global network infrastructures.
2QUIC Protocol Advantages
Unlike TCP, which requires multiple round trips for handshakes, QUIC utilizes 0-RTT capability to transmit application data while the handshake is still in progress. This mechanism eliminates the one-second latency bottleneck previously experienced in regions with poor connectivity, while also preventing head-of-line blocking by sending packets in multiple independent streams.
3Cloudflare and Infrastructure Integration
The transition to HTTP/3 was facilitated by Delivery Hero’s existing partnership with Cloudflare’s content delivery network. Reconfiguring the server-side infrastructure was straightforward, allowing the team to focus on client-side implementation. This global rollout ensured that 95 percent of users could leverage the new protocol, with automatic fallbacks to HTTP/2 for restricted networks.
4Android Networking Challenges
Implementing HTTP/3 on Android required integrating Google’s Cronet library. Initial tests revealed an 800-millisecond initialization delay at P90, which negated the 0-RTT speed benefits. To resolve this, engineers forked the code into a custom bridge, OKCronet, and overlapped the initialization process with other background tasks to maintain performance efficiency across the mobile application.
5Significant Performance Gains
The engineering efforts led to a 10x improvement in read latency, slashing P95 times from 1.2 seconds to 120 milliseconds. Handshake latency across the apps was reduced by 51 percent globally. In specific high-latency markets like Pakistan, response times were effectively cut in half, demonstrating the protocol's impact on unstable network environments.
6Congestion Control Limitations
Despite overall improvements, secondary screens faced latency issues in markets prone to packet loss. The team identified Cloudflare’s default Cubic congestion control algorithm as the primary culprit for these performance regressions. Testing revealed that Google’s BBR algorithm handled packet loss more effectively, prompting ongoing collaboration with Cloudflare to optimize these specific congestion settings.
7Global Market Context
Delivery Hero operates a diverse portfolio of regional apps, including Foodpanda, Yemeksepeti, Glovo, and PedidosYa, serving 60 million users across Africa, Latin America, and Asia. Uber is currently acquiring the company for $14.8 billion to integrate these services. Managing consistent performance across such varied regional network conditions remains a critical engineering priority.
8Strategic Engineering Takeaways
The project highlights that while HTTP/3 offers inherent speed advantages, successful deployment requires deep customization of client-side libraries and congestion control algorithms. By moving beyond default configurations, the team successfully mitigated regional network bottlenecks. This case study underscores the necessity of tailoring protocol implementations to specific hardware and connectivity constraints.