Vercel Announces Edge Functions v2 with Rust Support

- Vercel's move toward Rust isn't new; the company previously rebuilt parts of its standard function infrastructure from Node.js to Rust, which cut cold starts by 30% for smaller workloads and made larger ones up to 500ms faster at the 99th percentile. - Prior to native support, developers could run Rust on Vercel's edge by compiling it to WebAssembly (Wasm), a format supported since August 2022. Vercel's own tests showed that for computationally heavy tasks, Wasm could be more than twice as fast as equivalent JavaScript code. - The Next.js framework has been increasingly leveraging Rust for performance gains. Its compiler, SWC, is written in Rust and is up to 17 times faster than its predecessor, Babel, for JavaScript transpilation. - Edge Functions run on a lightweight V8 isolates runtime, which is different from a full Node.js environment and lacks features like direct file system access but enables faster startups. This contrasts with Vercel's standard Serverless Functions, which can run a full Node.js runtime. - A key competitor, Cloudflare Workers, also utilizes V8 isolates and has long supported Rust via WebAssembly, often cited for achieving near-instantaneous cold starts of less than 1 millisecond. Existing Vercel Edge Functions typically have cold starts under 50ms, a significant improvement over traditional serverless offerings. - The new tooling will likely integrate with Vercel's existing beta support for native Rust serverless functions, which uses a `Cargo.toml` file for configuration and places handler files in a root `/api` directory. - This update focuses on the "cold start" problem—the delay when a function is invoked for the first time after being idle. While Vercel's Edge Functions are already much faster than traditional serverless platforms, this aims to make them competitive with the near-zero cold starts of rivals.