Coalescing Connections to Improve Network Privacy and Performance

This post details a study and implementation of Connection Coalescing, a technique that allows subresources from different hostnames to be fetched over the same TLS connection. This reduces the number of TLS handshakes and SNI exposures, improving privacy and performance. The study involved dividing Cloudflare customers into control and experiment groups, enabling coalescing for the experiment group, and measuring the impact on TLS connections and page load times. Results showed a significant reduction in TLS connections for Chrome and a moderate reduction for Firefox, with no observed performance degradation.