How to improve your eCommerce Core Web Vitals step by step

When it comes to positioning an online store, many elements are at play: quality content, link strategy, user experience… but for some time now, loading speed and stability have become crucial SEO factors. This is precisely what the Core Web Vitals measure, a set of metrics created by Google to evaluate the quality of a website from the user’s perspective.

Improving these indicators not only impacts organic positioning but also conversion rates and customer retention. In this article, we explain how they work, how to diagnose them, and most importantly, how to optimize them step by step for your eCommerce.

Key Core Web Vitals Metrics and their importance in eCommerce

The Core Web Vitals are a set of three key metrics that assess user experience aspects such as loading time, interactivity, and visual stability. In March 2024, Google announced a significant change: the FID (First Input Delay) metric was replaced by INP (Interaction to Next Paint) as an official responsiveness indicator.

These are the current metrics comprising the Core Web Vitals:

• LCP (Largest Contentful Paint): measures the time it takes to load the main visible content. An acceptable LCP should be under 2.5 seconds.
• INP (Interaction to Next Paint): analyzes the latency of all user interactions during the session, not just the first. It should be below 200 milliseconds.
• CLS (Cumulative Layout Shift): detects unexpected design changes while the page is loading. A good value should be under 0.1.

For eCommerce, these indicators are particularly relevant: a poor score can result in abandoned carts, lower rankings, and poorer shopping experiences. Google uses these metrics as a ranking factor, making their optimization a technical and strategic necessity.

How to Measure Core Web Vitals

To measure the Core Web Vitals of your eCommerce, you can use free and accessible tools like PageSpeed Insights, which analyzes any URL and displays both laboratory and real-user data (drawn from the Chrome User Experience Report).

You can also use Google Search Console, where in the “Core Web Vitals” section, you will obtain a grouped report of URLs that need improvements.

For a more comprehensive and strategic analysis, Semrush allows you to audit your entire site, displaying in its technical module the values of LCP, INP, and CLS per page, along with detailed recommendations to optimize them.

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Steps to optimize the Core Web Vitals in your online store

Audit Your Website with Semrush

Access the “Site Audit” section and launch a technical analysis of your domain. Within the “Core Web Vitals” section, you will see a detailed breakdown of the metrics and suggestions to improve each one. This tool will help you to identify critical bottlenecks without needing to be an expert developer.

Optimize Images and Heavy Resources (LCP)

The content that takes the longest to load is usually a product image or main banner. Use modern formats like WebP, enable lazy loading for secondary content, and compress images without sacrificing quality. If you use a CMS like Shopify or WooCommerce, there are plugins that automate this process.

Reduce Main Thread Blocking (TBT)

Minimize unnecessary JavaScript, load scripts asynchronously, and prioritize critical resources. Less TBT implies greater responsiveness and, therefore, better INP in real situations.

Avoid Unexpected Layout Shifts (CLS)

One of the most common mistakes is not allocating the proper space for images, ads, or sliders. Ensure that you define fixed heights and widths in your CSS for these elements. This way, the layout does not “jump” during loading, improving the perception of stability.

Enable Caching and Use CDN

If your eCommerce receives visits from different countries, a Content Delivery Network (CDN) can drastically reduce loading times. Furthermore, enabling browser caching ensures that returning users load the website much faster.

Conclusion: Speed and Experience, Keys to Selling More

Improving Core Web Vitals is not just a technical matter, but a commitment to a better user experience, which translates into better positions on Google, higher conversion, and more loyalty. For eCommerce, where the first contact often decides the purchase, optimizing every millisecond counts.

Tools like Semrush facilitate diagnosis and action prioritization, allowing marketing and development teams to speak a common language based on real data. Because in electronic commerce, speed also sells.

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Remember: every second counts, every interaction matters. And in eCommerce, a good experience can be the difference between a click and a sale.