How Does SSR Improve Performance?

Server-side rendering (SSR) can significantly boost performance by handling the heavy lifting on the server side, so the browser doesn’t have to. 

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It speeds up page load times, especially for content-heavy or dynamic websites, because the server delivers fully-rendered HTML to the client. This can make your site feel faster and improve SEO.

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What Does SSR Do?

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Server-side rendering, or SSR, essentially means that when a user requests a web page, the server builds the page’s HTML before sending it back to the browser. So instead of your browser piecing together all the HTML, CSS, and JavaScript, the server does most of that. 

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It hands off the finished product (or mostly finished) to the user’s device. In comparison, client-side rendering (CSR) would offload that process to the browser itself, leading to a longer wait time before anything useful shows up on the screen.

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When it comes to performance, SSR shines. Here's why:

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1. Faster Initial Load Time

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When a browser gets an HTML page from an SSR setup, it immediately has the structure it needs to display content. There’s no waiting around for JavaScript to load and run before seeing anything meaningful. This is especially noticeable on slower devices or connections. 

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For example, if you’re loading a website with a lot of dynamic content, like a blog or an e-commerce platform, SSR speeds up that initial page load. You don’t want your users waiting for a spinner to disappear, right?

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According to Expert Beacon, SSR (with Puppeteer) has been shown to reduce First Contentful Paint (the time it takes for the first visual element to load) by up to 2.1x. An FCP of 1.8 seconds on a client-rendered site can drop to 850 milliseconds with SSR​.

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2. Better SEO

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Search engine crawlers love SSR because the content is already available when they come crawling. With CSR, crawlers might miss important content since they don’t always execute JavaScript effectively. 

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In SSR, the server sends fully-rendered HTML, which makes it easier for Google, Bing, and other search engines to index your pages. 

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Fun-Fact: Popular CMS platforms like WordPress and Webflow already use server-side rendering to gain an SEO advantage.  

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So, if SEO is a priority for you (and honestly, when isn’t it?), SSR gives you an edge. You’re more likely to rank better with SSR if your site is content-rich.

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3. Reduced Time-to-Interactive

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This is a big one, especially for websites that rely on user interactions. Because SSR renders the bulk of the page on the server, the time it takes for the site to become interactive—meaning users can click on buttons or type into forms—gets shorter. 

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Your users feel like they’re getting a snappier experience. You know the feeling when you load a page, but you can’t do anything because it’s still “thinking”? SSR helps eliminate that lag.

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4. Great for Static and Dynamic Content

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If you’re wondering when to use server-side rendering, the answer is: it depends on the nature of your content. SSR works wonders for dynamic content, frequently changing data, like news articles or e-commerce product listings. 

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If your site content updates often, SSR ensures users see the most current version without delay. And even for static sites, the faster initial load can still benefit from SSR.

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More info on static and dynamic content here.

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5. Lower Device Requirements

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Not everyone’s browsing on the latest phone or fastest internet. With CSR, the user’s device does more work, rendering the page locally. But SSR helps offload that processing to your server. 

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This is a huge win for users on low-powered devices or slower networks because their device isn’t handling as much heavy lifting. By delivering pre-rendered HTML, you help ensure your site runs smoothly across all types of devices.

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SSR for Dynamic Websites

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I once worked on a project for a content-heavy website with a lot of articles and images. Initially, the site was set up with client-side rendering. It looked fine on my high-end laptop, but we quickly noticed issues on slower devices. 

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The load times were slow, the pages took forever to display content, and mobile users were having a terrible time. On top of that, we saw our search rankings slipping, and I knew it had to be because the crawlers weren’t getting the full picture of our site’s content.

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We decided to switch to server-side rendering. It wasn’t an instant fix, but once we made the switch, the difference was night and day. 

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Pages loaded faster, users were engaging more (no one likes waiting for content to load), and our SEO performance bounced back because search engines could properly index the site.

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There was also case-study done by Infidigit on implementing SSR:

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Now, I’m not saying SSR is the magic bullet for every website, but if you’re working with a lot of dynamic content and care about performance and SEO, it’s definitely something to consider.

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When Should You Use Server-Side Rendering?

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SSR techniques aren’t necessary for every project. Here are some situations where SSR makes the most sense:

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• SEO-Dependent Sites: If search engine rankings are crucial to your business, SSR is almost a must-have. Google can easily crawl your content when it's rendered on the server.
• Content-Heavy Sites: If your website hosts a lot of content that updates frequently, such as blogs, news sites, or e-commerce stores, SSR ensures that users see the latest version of your content without a delay.
• Global Audiences: If your users are spread out across different parts of the world, SSR helps minimize latency, especially if you’re using a Content Delivery Network (CDN). The server delivers pre-rendered pages, cutting down on the time users in distant locations wait for the site to load.
• User-Interaction-Centric Sites: Websites or web apps that require a lot of interaction (think forms, buttons, dropdowns) can benefit from SSR’s reduced time-to-interactive, making for a smoother user experience.

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When SSR Might Not Be Worth It

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On the flip side, there are cases where SSR may not be worth the trouble. If your site is relatively simple, static, or doesn’t rely on SEO as much, you might not notice a significant improvement from SSR. Plus, implementing SSR can add complexity to your development process. 

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You’ll need to set up your backend to render HTML on the server, which can require more server resources and development time.

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I’ve also seen situations where SSR wasn’t worth the overhead. For smaller projects or apps that don’t rely on search engine traffic or have low content requirements, CSR or static site generation (SSG) could be just fine. So, it’s not a one-size-fits-all solution. You’ll want to weigh the benefits against the complexity.

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