Demystifying INP: New tools and actionable insights

This post provides a deep dive into optimizing Interaction to Next Paint (INP), a Core Web Vital metric. It clarifies common misunderstandings of INP, breaks down its anatomy (user interaction, other code, event handler, browser render), and offers actionable strategies for optimization. Key contributions include explaining how to minimize blocking code in event handlers and browser renders, detailing React performance optimizations (memoization, immutable context/props), and introducing the `await-interaction-response` module to separate user interaction acknowledgment from expensive operations. It also discusses advanced techniques for optimizing the browser render phase, such as CSS containment and list virtualization, and highlights real-world lessons learned from optimizing nextjs.org.