Rendering Strategies Compared — CSR, SSR, SSG, ISR, RSC, and More

In the evolving landscape of frontend development, various rendering strategies have emerged, each with its unique strengths and trade-offs. The choice of rendering strategy is a critical architectural decision that impacts aspects such as speed, interactivity, SEO, scalability, and more. This guide dissects these strategies, their evolution, and their optimal use-cases to equip you with the knowledge to make informed decisions.

The Evolution of Rendering

The early web was dominated by server-side rendering (SSR). Here, the server constructed the HTML page using languages like PHP, Rails, or Java and sent it over to the client. JavaScript was an optional add-on, employed for progressive enhancement.

With the advent of Single Page Applications (SPAs), rendering shifted to the client-side. Frameworks like Angular, React, and Vue facilitated this transition, enabling rich user experiences and interactivity. However, this led to issues with SEO and initial page load performance.

To mitigate these issues, hybrid rendering strategies were introduced, combining static, dynamic, and server-driven techniques. The evolution continues with the more recent techniques like React Server Components, Streaming, and Progressive Hydration.

1. Client-Side Rendering (CSR)

Working: In CSR, the server sends a minimal HTML shell to the client. The JavaScript bundle then loads, fetches data from APIs, and renders the UI client-side.

Benefits:

• Enables full interactivity, making it suitable for dashboards and apps with user authentication.
• Supports offline capabilities with service workers.

Drawbacks:

• Initial blank screen due to JavaScript loading and rendering.
• Not SEO-friendly by default, as search engine crawlers may not effectively parse JavaScript-rendered content.
• Bundle size becomes critical as it impacts load time.

Ideal for: Authenticated dashboards, internal tools, real-time apps

2. Server-Side Rendering (SSR)

Working: In SSR, the HTML page is rendered on the server at request time and sent to the client. The JavaScript then 'hydrates' the page to make it interactive.

Benefits:

• SEO-friendly as it delivers fully rendered HTML to the client.
• Faster first paint than CSR as it eliminates the need for client-side rendering.
• Supports dynamic content.

Drawbacks:

• Increased server load due to real-time rendering.
• Slower Time to First Byte (TTFB) compared to static content.
• Requires hydration logic to make the page interactive post-rendering.

Ideal for: Marketing pages, content portals, e-commerce product detail pages

3. Static Site Generation (SSG)

Working: In SSG, HTML is pre-rendered at build time for all routes and stored as static files, which are served upon request.

Benefits:

• Delivers high performance due to pre-rendered content.
• Fully cacheable, reducing server load.
• Virtually no server cost as it serves static files.

Drawbacks:

• Requires a rebuild to update content.
• Not suitable for highly dynamic data.
• Build times can be long for large sites.

Ideal for: Blogs, documentation, landing pages with infrequent updates

4. Incremental Static Regeneration (ISR)

Working: ISR is similar to SSG, but pages are regenerated on demand after a time-to-live (TTL) window or via an API/webhook.

Benefits:

• Combines the performance of static rendering with the freshness of dynamic content.
• Avoids full site rebuilds for updates.
• Scales well for large catalogs.

Drawbacks:

• Adds infrastructure complexity for on-demand regeneration.
• Possible cache staleness between regenerations.

Ideal for: E-commerce, content platforms, SEO-sensitive pages with dynamic data

5. React Server Components (RSC)

Working: RSC allows components to run on the server, sending serialized UI to the client. Only client-labeled components are hydrated.

Benefits:

• Reduces bundle size by eliminating client-side rendering for non-interactive components.
• Enables seamless data fetching, reducing the need for client-side data fetching.
• Minimizes client-side JavaScript for non-interactive parts.

Drawbacks:

• Still in early stages of adoption, so ecosystem support may be limited.
• No access to browser APIs for server components.
• Complexity in managing client and server components.

Ideal for: Modern full-stack apps with mixed interactivity

6. Streaming

Working: In streaming, HTML is progressively sent to the client as components render. It can be combined with SSR and RSC.

Benefits:

• Provides fast First Contentful Paint (FCP) by sending HTML in chunks.
• Enables non-blocking data loading.
• Offers better performance on slow networks.

Drawbacks:

• Requires server/edge support for streaming.
• Suspense boundaries must be carefully designed to prevent incomplete UI rendering.

Ideal for: Content-heavy or nested apps, article pages, storefronts

Comparison Table

| Strategy | SEO | Performance | Interactivity | Personalization | Best for | |----------|-----|-------------|----------------|-----------------|----------| | CSR | ❌ | ⚠️ Slow | ✅ Full | ✅ | Dashboards | | SSR | ✅ | ⚠️ Medium | ✅ Full | ✅ | Marketing | | SSG | ✅ | ⚡ Fast | ✅ Full | ❌ | Blogs | | ISR | ✅ | ⚡ Fast | ✅ Full | ⚠️ Limited | E-commerce | | RSC | ✅ | ⚡⚡ | ✅ Hybrid | ⚠️ Depends | Apps | | Streaming| ✅ | ⚡⚡ | ✅ Gradual | ⚠️ Yes | Articles |

Conclusion: Strategic Composition

There is no one-size-fits-all rendering strategy. The best approach often involves a composition of multiple strategies:

• Use SSG or ISR for content-heavy, SEO-critical pages.
• Use SSR + Streaming for dynamic content.
• Use CSR for authenticated or real-time features.
• Use RSC and Partial Hydration to reduce bundle size.
• Use Edge Functions to personalize at scale.

The choice of rendering strategy should be based on your users' needs, your infrastructure capacity, and your business objectives — not just developer familiarity or convenience. Remember, your rendering strategy forms a crucial facet of your UX strategy. So, make it count.