Our experiment successfully demonstrated that HTTP3 significantly improved latency at the 90th percentile and above. Even though HTTP3 noticeably reduces latencies for only 10% of our users, these will be the users who suffer from high latencies and will appreciate improvement the most. The biggest beneficiaries of HTTP3 would be our international users, since the highest latencies are disproportionally found outside of North America.
We gained two major insights from our large-scale experiment:
- The benefits of 0RTT are less important because nearly all connections to dropbox.com are long-lived.
- The way HTTP3 handles head-of-line blocking significantly reduced latencies, especially in networks where packets drops are more likely to occur.