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01What SSR actually is
Server-Side Rendering (SSR) is a technique used to render web pages on the server and then deliver them to the client as pre-rendered HTML. The browser does not wait for an application bundle to invent the first screen. It receives markup it can paint.
This approach offers benefits such as faster initial load times and enhanced search engine optimization (SEO). However, it comes with associated costs. The utilization of SSR necessitates additional server resources, including processing power and memory, for rendering the initial HTML of a page. Moreover, incorporating dynamic content and server-side logic can further escalate the expenses of maintaining an SSR application.
02How SSR works
Server Side Rendering eliminates the requirement to download and run application code before anything is visible, allowing websites to load quickly. The HTML of the site is rendered in a defined programming pattern. These are the steps.
- 01Initiation. The user starts their browser and requests to open a webpage.
- 02Server processing. The server generates rendered content in an HTML file and sends it to the user. CSS is presented on the browser, but the page remains non-interactive.
- 03Downloading JavaScript. Simultaneously, the browser begins downloading the page's JavaScript, which is readily accessible on the server.
- 04Enabling interactivity. Once the JavaScript is downloaded, the user gains the ability to interact with various elements on the site.
- 05JavaScript execution. The browser executes the JavaScript, fully rendering the Document Object Model (DOM).
- 06Fully functional page. With all elements loaded and the JavaScript executed, the page becomes fully functional and responsive to the user's interactions throughout their journey.
03Server-side rendering advantages
The case for SSR is commercial, not doctrinal. Each advantage below is a ranking, conversion or measurement argument — not a framework preference.
Faster load time
SSR only updates the parts of the HTML that need updating, leading to faster page transitions and quicker First Contentful Paint (FCP). Even users with slow internet connections or outdated devices can immediately see the page — which is beneficial for SEO and for paid traffic that lands on a cold mobile session.
Easy to index
Indexing SSR sites is much easier for search engines than client-side rendered sites. The content is rendered before the page is loaded, eliminating the need for search engines to run JavaScript to read and index it. That is the difference between a crawl that finds the product and a crawl that finds an empty shell.
Ideal for static websites
SSR is excellent for static web pages as it is faster to pre-render a static page on the server before sending it to the client. Where the page does not change per request, the same work can be done at build time (SSG) and cached at the edge — SSR's cheaper cousin, and the pattern this site ships.
More accurate user metrics
SSR enables quick and accurate gathering of user metrics, providing insights into user navigation and interactions to help continually improve the user interface and experience. First paint is real; a client-only app that never hydrates on a slow device reports a bounce that was actually a blank screen.
04Server-side rendering disadvantages
The bill arrives after the demo. Treat each of these as a design constraint, not a reason to abandon the pattern.
| Cost | What you feel | When it bites |
|---|---|---|
| Server load | CPU and memory per request | Large, personalised applications |
| Running expense | Hosting, debug, maintain | Dynamic content + server logic |
| Compatibility | Libraries that assume a window | Third-party JS widgets |
| Interactivity lag | Visible but not clickable | Heavy client hydration |
| Caching | HTML unique per visitor | Uncached, session-bound pages |
Higher server load for bigger applications
Larger and more complex applications increase the server load, potentially leading to longer loading times due to a single bottleneck. Every request that must be rendered on the origin competes for the same cores. At catalogue scale, that bottleneck is the product, not a misconfigured CDN.
Increase in expenses
SSR can become complex and expensive to maintain, debug and host, leading to higher running costs. You are now operating a render farm, not a static file host. The engineering time to keep hydration, caching and streaming coherent is the line item finance never sees in the original pitch.
Compatibility issues
SSR may be incompatible with some third-party libraries and tools, including JavaScript code that assumes window on first evaluation. Anything that touches the DOM at import time will crash the render, and the workaround is usually a client-only island — which is how the critical path grows back.
Slow page rendering inactivity
Despite allowing immediate page viewing, users may still need to wait for JavaScript download to interact with the page. A form that looks ready and is not is worse than a spinner. Budget Time to Interactive as tightly as First Contentful Paint.
Inefficient caching
SSR makes efficient caching more challenging, as each page's HTML is different, leading to longer load times for uncached pages. Personalisation, A/B flags and session cookies all punch holes in the cache. If most of the page is the same for everyone, render the shared shell once and hydrate only the exception.
05When we ship it
Use SSR (or SSG that looks like SSR to the crawler) when the first HTML must contain the thing a buyer or a bot came for: product copy, a regulated disclosure, a landing surface that paid media is buying. Do not use it as a default for dashboards, authenticated tools, or anything whose HTML is unique per user and worthless to index.
- Ship HTML for the money page. Landing, product, article, pricing — the surfaces crawlers and cold sessions hit.
- Cache what does not change per request. Build-time or edge cache beats origin render every time.
- Hydrate only what is interactive. The rest of the tree does not need a JavaScript runtime.
- Measure TTFB and TTI, not just LCP. SSR can win paint and lose the click if the bundle is still a brick.
Next step
Get a rendering-path teardown
We map which templates should be static, which must render on the origin, and which are leaking TTI after the HTML already arrived — then hand you the budget as a mergeable document.
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