NextJS Rendering Strategies: Understanding SSG, SSR, ISR, and PPR

Next.js has revolutionized how we think about rendering strategies in React applications. With four powerful rendering methods at your disposal—Static Site Generation (SSG), Server-Side Rendering (SSR), Incremental Static Regeneration (ISR), and the new Partial Prerendering (PPR)—choosing the right approach can significantly impact your application's performance, SEO, and user experience.

In this comprehensive guide, we'll explore each rendering strategy, understand their strengths and limitations, and learn when to use each one for optimal results.

Table of Contents

• Static Site Generation (SSG)
• Server-Side Rendering (SSR)
• Incremental Static Regeneration (ISR)
• Partial Prerendering (PPR)
• Comparison Chart
• When to Use Each Strategy
• Conclusion

Static Site Generation (SSG)

What is SSG?

Static Site Generation pre-renders pages at build time, creating static HTML files that can be served instantly from a CDN. This approach offers the fastest possible page loads and excellent SEO performance.

How It Works

// app/blog/[slug]/page.js
async function BlogPost({ params }) {
  const post = await fetchBlogPost(params.slug);

  return (
    <article>
      <h1>{post.title}</h1>
      <div>{post.content}</div>
    </article>
  );
}

export async function generateStaticParams() {
  const posts = await fetchAllBlogPosts();

  return posts.map((post) => ({
    slug: post.slug,
  }));
}

export default BlogPost;

Pros and Cons

✅ Pros:

• Lightning-fast performance: Pre-built HTML serves instantly
• Excellent SEO: Complete HTML available for crawlers
• Cost-effective: Can be hosted on static hosting services
• Scalability: CDN distribution handles high traffic effortlessly
• Reliability: No server-side computation during requests

❌ Cons:

• Build time increases with the number of pages
• Content updates require rebuilds
• Not suitable for frequently changing data
• Limited personalization capabilities

Best Use Cases

SSG is perfect for: Marketing websites • Documentation sites • Blog posts • Product catalogs with stable inventory • Portfolio websites

Server-Side Rendering (SSR)

What is SSR?

Server-Side Rendering generates HTML on each request, ensuring users always receive the most up-to-date content. The server processes the request, fetches fresh data, and returns fully rendered HTML.

How It Works

// app/dashboard/page.js
import { headers, cookies } from "next/headers";

async function DashboardPage() {
  const session = await getSession();
  const userData = await fetchUserData(session.userId);

  return <DashboardLayout data={userData} />;
}

export default DashboardPage;

Pros and Cons

✅ Pros:

• Always fresh data: Content is up-to-date on every request
• Dynamic content support: Perfect for personalized experiences
• SEO-friendly: Full HTML available for search engines
• No build time constraints: Pages generated on-demand

❌ Cons:

• Slower initial load: Server processing adds latency
• Higher server costs: Requires compute resources for each request
• Scalability challenges: Server load increases with traffic
• Geographic latency: Distance from server affects performance

Best Use Cases

SSR is ideal for: User dashboards • Real-time data displays • Personalized content • Search results pages • Social media feeds

Incremental Static Regeneration (ISR)

What is ISR?

ISR combines the benefits of SSG and SSR by serving static pages while revalidating them in the background. Pages can be updated after deployment without rebuilding the entire site.

How It Works

// app/products/[id]/page.js
export const revalidate = 60; // seconds

async function ProductPage({ params }) {
  const product = await fetchProduct(params.id);

  return (
    <div>
      <h1>{product.name}</h1>
      <p>{product.description}</p>
      <span>{product.price}</span>
    </div>
  );
}

export default ProductPage;

ISR Revalidation Flow

1. User Request → Check if cache is valid
2. If valid → Serve cached page
3. If stale → Serve stale page + regenerate in background
4. Update cache → Next user gets fresh page

Pros and Cons

✅ Pros:

• Best of both worlds: Static performance with dynamic updates
• Gradual updates: No need for full site rebuilds
• Stale-while-revalidate: Users get cached content while updates happen
• Scalable: CDN-friendly with periodic updates
• Fallback support: Can generate pages on-demand

❌ Cons:

• Eventual consistency: Updates aren't immediate
• Complexity: More complex caching strategies
• Potential for stale content: Users might see outdated information briefly
• Revalidation costs: Background regeneration uses resources

Best Use Cases

ISR excels at: E-commerce product pages • News websites • Content that updates periodically • Large sites with thousands of pages • Blogs with occasional updates

Partial Prerendering (PPR)

⚠️ Experimental Feature: PPR is currently experimental and available in Next.js 14+. Enable it in your next.config.js with experimental: { ppr: true }

What is PPR?

Partial Prerendering is Next.js's newest experimental feature that combines static and dynamic rendering within a single page. It prerenders the static shell of a page while streaming dynamic content.

How It Works

// app/page.js
import { Suspense } from "react";

// Static shell component
export default function Page() {
  return (
    <div>
      <h1>Welcome to our store</h1>
      <StaticHero />

      {/* Dynamic content wrapped in Suspense */}
      <Suspense fallback={<ProductsSkeleton />}>
        <DynamicProducts />
      </Suspense>

      <Suspense fallback={<div>Loading user...</div>}>
        <UserGreeting />
      </Suspense>

      <StaticFooter />
    </div>
  );
}

// Dynamic component (automatically detected)
async function DynamicProducts() {
  const products = await fetchLatestProducts();
  return <ProductGrid products={products} />;
}

async function UserGreeting() {
  const user = await getCurrentUser();
  return <div>Welcome back, {user.name}!</div>;
}

PPR Rendering Flow

1. Initial Request → Serve static shell instantly
2. Display Loading States → Show fallback components
3. Stream Dynamic Content → Progressive enhancement
4. Full Page Rendered → Complete user experience

Pros and Cons

✅ Pros:

• Instant static shell: Core layout loads immediately
• Progressive enhancement: Dynamic content streams in
• Optimal performance: Combines static speed with dynamic freshness
• Automatic optimization: Next.js determines what to prerender
• Better UX: No layout shift with proper loading states

❌ Cons:

• Experimental feature: Still evolving and may change
• Learning curve: Requires understanding of React Suspense
• Limited browser support: Requires modern browsers for streaming

Best Use Cases

PPR is perfect for: E-commerce homepages • Dashboard layouts with dynamic widgets • News sites with static navigation and dynamic content • SaaS applications with mixed content requirements

Comparison Chart

When to Use Each Strategy

Quick Decision Guide

Choose SSG when:

• ✓ Content rarely changes
• ✓ SEO is critical
• ✓ You want the fastest possible performance
• ✓ Hosting budget is limited
• ✓ Building documentation or marketing sites

Choose SSR when:

• ✓ Data must always be fresh
• ✓ Content is highly personalized
• ✓ You're building user-specific pages
• ✓ Real-time data is essential
• ✓ SEO is important for dynamic content

Choose ISR when:

• ✓ Content updates periodically
• ✓ You have many pages (thousands+)
• ✓ You want static performance with updates
• ✓ Building e-commerce or content sites
• ✓ Need balance between performance and freshness

Choose PPR when:

• ✓ Pages have clear static/dynamic sections
• ✓ You want the best possible UX
• ✓ Initial page load speed is critical
• ✓ Building modern web applications
• ✓ Comfortable with experimental features

Implementation Tips

Mixing Strategies

Next.js allows you to use different rendering strategies for different pages:

// pages/index.js - Static homepage
export async function getStaticProps() {
  return {
    props: {
      /* ... */
    },
  };
}

// pages/dashboard.js - Dynamic dashboard
export async function getServerSideProps() {
  return {
    props: {
      /* ... */
    },
  };
}

// pages/products/[id].js - ISR for products
export async function getStaticProps() {
  return {
    props: {
      /* ... */
    },
    revalidate: 3600,
  };
}

Performance Monitoring

Monitor Core Web Vitals to ensure your chosen strategy delivers expected performance:

• LCP (Largest Contentful Paint): SSG and PPR typically excel
• FID (First Input Delay): All strategies can achieve good scores
• CLS (Cumulative Layout Shift): Proper loading states are crucial

Caching Strategies

// Configure CDN caching headers
export async function getServerSideProps({ res }) {
  res.setHeader(
    "Cache-Control",
    "public, s-maxage=10, stale-while-revalidate=59",
  );

  return {
    props: {
      /* ... */
    },
  };
}

// data caching
import { unstable_cache } from "next/cache";

const getCachedUser = unstable_cache(async (id) => getUserById(id), ["user"], {
  revalidate: 3600,
});

Conclusion

Next.js's rendering strategies offer unprecedented flexibility in building modern web applications. There's no one-size-fits-all solution—the best approach depends on your specific use case, performance requirements, and user expectations.

Key Takeaways:

• Start with SSG for static content
• Leverage SSR for dynamic user experiences
• Adopt ISR for scalable content sites
• Experiment with PPR for ultimate performance optimization

Remember, you can mix and match these strategies within a single application to create the perfect balance of performance and functionality.

As you build your Next.js applications, continuously evaluate your rendering choices based on real user metrics and adjust accordingly. The beauty of Next.js lies in its flexibility—you're never locked into a single approach.

Further Reading

• Next.js Documentation on Rendering
• Web Vitals and Performance Metrics
• React Server Components
• Edge Runtime in Next.js
• Next.js Caching Strategies