Performance in React and Next.js

Presented at Next.js Conf 2023. This talk by Lydia Hallie explores how concurrent features introduced in React 18, and specifically how Next.js leverages these for improved performance with the App Router. It covers long tasks, the main thread, total blocking time, interaction to next paint, and how concurrent rendering allows for marking updates as low priority. The discussion also touches on React Server Components, suspense for data fetching, and how Next.js integrates these features for a better developer and user experience.