In the ever-evolving landscape of digital marketing, website performance has become a critical factor in determining online success. One of the most crucial aspects of this performance is a set of metrics known as Core Web Vitals. These metrics, introduced by Google, measure the user experience on a website, focusing on loading performance, interactivity, and visual stability. In this guide, we will walk you through the process of optimising your website for Core Web Vitals, ensuring that your site not only meets but exceeds user expectations.
Understanding Core Web Vitals
Before diving into the optimisation process, it is essential to understand what Core Web Vitals are and why they matter. Core Web Vitals consist of three key metrics:
Largest Contentful Paint (LCP): Measures loading performance. To provide a good user experience, LCP should occur within 2.5 seconds of when the page first starts loading.
First Input Delay (FID): Measures interactivity. To ensure a good user experience, pages should have an FID of less than 100 milliseconds.
Cumulative Layout Shift (CLS): Measures visual stability. To provide a good user experience, pages should maintain a CLS of less than 0.1.
These metrics are crucial because they directly affect how users perceive the performance of your website. A site that loads quickly, responds swiftly to user inputs, and remains visually stable is more likely to keep visitors engaged and reduce bounce rates.
Step 1: Measuring Your Current Core Web Vitals
The first step in optimising your website for Core Web Vitals is to measure your current performance. There are several tools available that can help you do this:
Google PageSpeed Insights: This tool provides a detailed analysis of your website’s performance, including Core Web Vitals scores for both mobile and desktop versions of your site.
Google Search Console: The Core Web Vitals report in Search Console gives you an overview of how your site is performing across all pages, highlighting areas that need improvement.
Lighthouse: Integrated into Chrome DevTools, Lighthouse allows you to run audits on specific pages, providing insights into performance, accessibility, and SEO, including Core Web Vitals.
After running these tools, you will have a clear picture of where your website stands in terms of LCP, FID, and CLS. This data will serve as the foundation for your optimisation efforts.
Step 2: Optimising Largest Contentful Paint (LCP)
LCP is a critical metric because it measures how quickly the main content of your page loads. Here are some strategies to improve LCP:
Optimise Server Response Times
A slow server response time can significantly delay the loading of your website’s content. To reduce server response times:
Use a Content Delivery Network (CDN): CDNs store copies of your website on servers around the world, reducing the distance between the server and the user, thereby speeding up load times.
Optimise Server Configuration: Ensure that your server is configured to handle requests efficiently. This might involve optimising database queries, using server-side caching, or upgrading your hosting plan.
Minimise HTTP Requests: Reduce the number of HTTP requests by combining files (such as CSS and JavaScript) and removing unnecessary elements from your pages.
Optimise Resource Load Times
Resources like images, videos, and fonts can significantly impact LCP. To optimise resource load times:
Optimise Images: Compress images using tools like TinyPNG or ImageOptim, and consider using modern formats like WebP, which offer better compression without sacrificing quality.
Preload Important Resources: Use the
<link rel="preload">tag to prioritise loading critical resources, such as the hero image or main font, which can improve LCP.Lazy Load Offscreen Content: Implement lazy loading for images and videos that are not immediately visible to users. This ensures that only the content above the fold is loaded initially, speeding up the LCP.
Minimise Render-Blocking Resources
Render-blocking resources, such as CSS and JavaScript, can delay the rendering of your page’s content. To minimise their impact:
Inline Critical CSS: Instead of loading a large CSS file, consider inlining the critical CSS directly into the HTML. This reduces the need for a separate HTTP request.
Defer Non-Critical JavaScript: Use the
deferattribute to ensure that JavaScript files load after the main content of your page. This prevents them from blocking the rendering process.
Step 3: Optimising First Input Delay (FID)
FID measures the time it takes for your website to respond to a user’s first interaction, such as clicking a button or a link. A low FID is essential for maintaining a responsive user experience. Here’s how to improve it:
Reduce JavaScript Execution Time
Long JavaScript execution times can delay user interactions, leading to a higher FID. To reduce JavaScript execution time:
Minimise JavaScript: Remove any unnecessary JavaScript and split long tasks into smaller, asynchronous tasks. Tools like Webpack can help bundle and minify your JavaScript files, reducing their size.
Use Web Workers: Web Workers allow you to run JavaScript in the background without blocking the main thread. This ensures that heavy JavaScript tasks do not interfere with user interactions.
Optimise Event Listener Usage
Event listeners can slow down the processing of user inputs, especially if they are not used efficiently. To optimise event listener usage:
Avoid Complex Event Listeners: Simplify the logic within event listeners and avoid running heavy computations in response to user inputs.
Use Passive Event Listeners: Passive event listeners inform the browser that the event listener will not prevent the default action, allowing the browser to improve performance.
Optimise Web Fonts
Web fonts can delay the rendering of text, leading to higher FID. To optimise web fonts:
Use Font Display Swap: The
font-display: swap;property allows text to be displayed immediately using a fallback font until the custom font is loaded. This reduces the impact of web fonts on FID.Preload Key Fonts: Similar to images, preloading key fonts ensures they are available as soon as the browser needs them, reducing delays in text rendering.
Step 4: Optimising Cumulative Layout Shift (CLS)
CLS measures the visual stability of your website by tracking how much the layout shifts during the loading process. A low CLS score is vital for preventing frustrating user experiences. Here’s how to improve CLS:
Specify Size Attributes for Media
One of the most common causes of layout shifts is the absence of size attributes for images, videos, and iframes. When the browser doesn’t know the size of these elements in advance, it has to adjust the layout as they load. To prevent this:
Set Width and Height Attributes: Always define the width and height attributes for images and videos in your HTML. This helps the browser allocate the correct amount of space while the content loads.
Use CSS Aspect Ratio Boxes: For responsive images or videos, use CSS to maintain the aspect ratio and prevent layout shifts.
Avoid Inserting Content Above Existing Content
Another common cause of layout shifts is the insertion of new content above existing content, pushing it down the page. To avoid this:
Avoid Dynamic Content Above the Fold: Do not insert ads, banners, or other dynamic content at the top of the page after the main content has loaded.
Reserve Space for Ads: If you must include dynamic content, reserve space for it ahead of time using CSS. This prevents the content from shifting when the dynamic element loads.
Optimise Web Fonts to Avoid Flash of Unstyled Text (FOUT)
Flash of unstyled text (FOUT) occurs when the browser initially displays fallback fonts, then switches to the custom font once it loads. This switch can cause layout shifts. To mitigate this:
Use Font Display Optional: The
font-display: optional;property allows the browser to render fallback fonts if the custom font takes too long to load, reducing the chances of layout shifts.Preload Fonts: As mentioned earlier, preloading fonts ensures they are available as soon as the browser needs them, preventing layout shifts caused by font loading.
Step 5: Continuous Monitoring and Improvement
Optimising your website for Core Web Vitals is not a one-time task; it requires ongoing monitoring and adjustments. Here’s how to ensure your site remains optimised:
Regularly Use Performance Tools: Continue to use tools like Google PageSpeed Insights, Lighthouse, and Google Search Console to monitor your Core Web Vitals. Set up alerts for any significant drops in performance.
Conduct User Testing: User testing can provide valuable insights into how real users experience your website. Tools like Hotjar or Crazy Egg can help you understand how users interact with your site and identify any performance issues.
Stay Updated with Best Practices: Web technologies and best practices are constantly evolving. Keep abreast of the latest developments in web performance optimisation by following industry blogs, attending webinars, and participating in online communities.
Optimising your website for Core Web Vitals is essential for delivering a superior user experience, improving search engine rankings, and ultimately achieving online success. By following the step-by-step guide outlined above, you can ensure that your website meets Google’s standards for loading performance, interactivity, and visual stability.
Remember, optimisation is an ongoing process. Regularly monitor your website’s performance, stay informed about the latest best practices, and continuously make improvements to maintain a competitive edge in the digital landscape. By doing so, you’ll not only meet but exceed the expectations of your users, fostering greater engagement and driving long-term success.