Explore Angular’s incremental hydration with @defer to bridge the LCP–TTI gap, reduce TBT, and build faster, smoother SSR apps.

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Incremental hydration in Angular allows SSR apps to render content instantly while activating interactivity only when needed, reducing the gap between visual rendering (LCP) and interactivity (TTI). Using the @defer block with triggers like 'on idle', 'on viewport', 'on interaction', and 'on hover', developers can control when components hydrate, keeping the main thread free and reducing Total Blocking Time. The technique includes automatic event replay to capture user interactions before hydration completes, requires proper HTML structure to avoid re-rendering, and maintains SEO benefits since content is server-rendered. Implementation involves configuring provideClientHydration with withIncrementalHydration, understanding parent-child hydration hierarchy, and debugging hydration mismatches using Angular DevTools.

Incremental Hydration in Angular: Build SSR Apps That Feel Instantly Interactive

5. Architecture: Nested blocks and constraints