What is Progressive Rendering in Web Development

What is Progressive Rendering?

Progressive Rendering is technique where page content parts are displayed as they load, not after full document load.

Goal — make site or application perceptually fast: user sees something useful as early as possible.

Why is This Important?

User can start interacting with page before full load:

• Reduces First Contentful Paint (FCP)
• Improves perceived speed
• Increases UX, especially in poor network conditions

Main Progressive Rendering Techniques

Lazy Loading (Deferred Loading)

• Load only visible content, rest — as you scroll or request.
• Applied to images, videos, heavy components.

<img loading="lazy" src="image.jpg" alt="..." />

In React: React.lazy, Suspense, dynamic import().

Streaming (HTML Streaming, SSR Streaming)

• Server gradually sends HTML to browser.
• Allows starting render before all content is ready.

// Example in React 18 with SSR streaming
import { renderToPipeableStream } from "react-dom/server";

Very useful in SSR and large applications.

Skeletons and Placeholders

Instead of empty blocks skeletons or placeholders are shown while data is loading.

{isLoading ? <SkeletonCard /> : <ProductCard data={data} />}

Progressive Hydration

In React/Next.js you can hydrate only needed page parts first, rest later.

<Script strategy="lazyOnload" />

Works with server-side rendering and improves time to interactivity.