Cloudflare Rewrites Core System in Rust for Enhanced Performance

Cloudflare has overhauled its primary system, FL, by rewriting it in Rust. The FL system, crucial for security rule application, DDoS attack mitigation, and traffic routing, previously operated on LuaJIT and OpenResty. The newly developed version, FL2, utilizes Rust and Oxy, delivering notable improvements: a 10-millisecond reduction in average response time, a 25% increase in performance, and over 50% savings in CPU and memory usage. The complete migration to FL2 is expected by the end of the year, with the old system retiring in early 2026. For more details, visit the Cloudflare blog.