Bun runtime on Vercel Functions

What this post added

Introduces Bun as a new runtime option for Vercel Functions, enabling developers to select between Node.js and Bun via `vercel.json`. Details performance benefits of Bun, citing a 28% reduction in average latency for CPU-bound Next.js rendering workloads compared to Node.js. Explains the technical reasons for Bun's performance gains (Zig-based architecture, optimized I/O and scheduling). Provides configuration examples for `vercel.json` and Hono. Discusses performance characteristics and tradeoffs between Bun and Node.js, including compatibility and cold start considerations. Mentions benchmark results and ongoing optimization efforts.