Programming Tutorials

  The pendulum of web architecture has swung from server-side monoliths to client-side SPAs, and now settles on a hybrid middle ground. However, the choice between   React Server Components (RSC)   (exemplified by Next.js App Router) and   Islands Architecture   (exemplified by Astro) is rarely about preference; it is about the physics of the browser main thread. Architects and Tech Leads often face a paralysis where interactivity requirements conflict with Core Web Vitals (specifically Interaction to Next Paint - INP, and Total Blocking Time - TBT). This post delineates exactly when to use which architecture and provides the implementation patterns required to maximize performance in both. The Root Cause: The Hydration Cost Curve The fundamental problem is not "how to render HTML," but  how to reconcile the Virtual DOM with the Real DOM . The Monolith Hydration (SPA):  The browser downloads HTML, then downloads a massive JS bundle, parses it, executes...