How Does Implementing Server-Side Rendering (SSR) Improve Core Web Vitals, and What Are the Best Practices for SSR Setup?


Server-Side Rendering (SSR) can significantly improve Core Web Vitals, a set of real-world metrics that target critical aspects of user experience such as loading, interactivity, and visual stability. Employing SSR can assist with the initial page load, improve the Largest Contentful Paint (LCP), and boost the web page's Search Engine Optimization (SEO) performance. The best practices for setting up SSR include using a framework that supports it, proper server configuration, efficient rendering methods, and optimization of static assets.

Enhancing Core Web Vitals with SSR

Largest Contentful Paint (LCP)

SSR is key in improving the LCP, a Core Web Vitals measurement that focuses on load time for the bulk of webpage content. Faster LCP times improve user experience by showing necessary content quicker than normal. SSR achieves this by sending a fully rendered page to the client, reducing JavaScript required on the client-side and in turn speeding up load times [LCP, 2021].

First Input Delay (FID) and Cumulative Layout Shift (CLS)

SSR can also assist with other Core Web Vitals such as First Input Delay (FID) and Cumulative Layout Shift (CLS). By rendering more content server-side, it reduces the amount of work needed on the client-side, leading to faster interactivity (FID) and less layout shift while loading (CLS) [FID, 2021] [CLS, 2021].

SEO Performance

SSR can also enhance SEO performance as search engines base their rankings on how quickly and efficiently they can crawl a website's content. Since SSR serves fully-rendered pages to the client, search engines can efficiently parse and rank the pages [SEO and JavaScript Rendering, 2020].

SSR Setup Best Practices

Selecting a Suitable Framework

Many modern web frameworks such as Next.js and Vue.js offer built-in SSR capabilities, making it easier to get started with SSR. When choosing a framework, one must consider factors like the application's complexity, maintainability, and learning curve [Next.js, 2022] [Vue.js SSR Guide, 2022].

Proper Server Configuration

When SSR is used, the server must be configured to handle the rendering process effectively. This involves setting up a Node.js server to render and serve pages, as well as routing requests correctly. Using middleware like Express.js can streamline this process [Node.js Overview, 2022] [Express.js, 2022].

Efficient Rendering Methods

Optimizing the server's rendering process is critical for boosting performance. Techniques such as code splitting and lazy loading can be employed to only download necessary code and data, reducing the load time [Code Splitting with Suspense, 2021].

Optimization of Static Assets

Scripts, stylesheets, images, and other static assets should be adequately optimized for quicker delivery and minimized bandwidth use, such as through compression and proper cache configuration [Image Optimization, 2021] [HTTP Cache, 2021].


Having a server-side rendering setup has become crucial in improving Core Web Vitals and boosting a website's search engine performance. Following the outlined best practices ensures that pages are delivered faster and improves the overall user experience.