React Server Components vs Client Components

The single biggest performance mistake in Next.js App Router projects is adding 'use client' to every component by default. Server Components ship zero JavaScript to the browser, have direct backend access, and render faster on every metric. The rule is simple: only push interactivity to the leaves of your component tree. A page layout, a card grid, a static text block — these should all be Server Components. Only the toggle button, the form input, or the animation wrapper needs 'use client'. On a recent enterprise dashboard project, refactoring from a client-heavy architecture to a server-first approach reduced the JavaScript bundle from 340kb to 87kb — a 74% reduction. Initial page load dropped from 2.1 seconds to 0.6 seconds on a 3G connection. The practical workflow: start every component as a Server Component, then add 'use client' only when the compiler errors on useState, useEffect, or event handlers. This forces intentionality about what actually needs client-side interactivity. Source: enterprise dashboard refactor, 2026.