The result is FL2, a full rewrite of its 15-year-old FL platform, which the company says now runs millions of customer sites up to 25 per cent faster.
In a press release Cloudflare said: “We’ve spent the last year rebuilding major components of our system. We’ve just slashed the latency of traffic passing through our network for millions of our customers.”
The outfit's internal metrics show a 10 millisecond reduction in median response time, a serious improvement given the scale of Cloudflare’s operation.
The revamp came with a complete architectural shift. Out went NGINX, OpenResty and LuaJIT. In came Rust, and with it Oxy, Cloudflare’s next-generation proxy framework.
The outfit said: “We write a lot of Rust, and we’ve gotten pretty good at it. Rust’s safety guarantees eliminate entire classes of bugs like memory leaks and data races.
Rebuilding a platform of this size wasn’t a weekend job. More than 100 engineers worked on FL2, gradually routing customer traffic through it from early 2025. To make the transition bearable, Cloudflare bolted a compatibility layer onto the old FL1 system, allowing engineers to swap Lua modules for Rust ones without maintaining two versions at once.
The gains are measurable and massive. FL2 uses less than half the CPU and memory of its predecessor, largely because it no longer has to shuffle data between C, Lua, and Rust layers. The new system also performs less redundant work thanks to clever module filtering.
Independent tests like CDNPerf back up the company’s claims of faster websites. Beyond the performance leap, Cloudflare says the rewrite has made its network far more secure. Rust’s compile-time checks and strict type system prevent whole categories of memory errors, and its modular design lets engineers push changes with greater confidence.
By early 2026, the firm plans to switch off FL1 entirely. Once the migration is complete, everything in the system will be modular, Rust-based, and production-tested. After that, Cloudflare says, it can really start tuning the engine.