A high-performance experimentation engine was built for vercel.com using Next.js and Vercel Edge Config. The goal was to create a culture of growth by leveraging A/B testing and experiments, while minimizing impact on end-users. The engine uses Edge Config to read dynamic data close to users, allowing for fast page loads with zero Cumulative Layout Shift (CLS). It also provides a standardized path to effective, high-performance experiments, including type safety, pre-rendering experiment variations, and dynamic routing. The engine's data fetching utilities ensure that users end up on the correct page variations, while its React context makes it easy to track analytics and collect data about experiments. With this engine, vercel.com can ship and iterate on experiments quickly and safely, without sacrificing performance or user experience.