Technical SEO: Understanding and Optimizing Core Web Vitals

At a Glance: The 3 Core Web Vitals

Why Core Web Vitals Are Essential in Digital Marketing

Core Web Vitals are metrics used by Google to assess the user experience on a website. They are part of technical SEO , an often-overlooked but crucial pillar of a company's digital performance.

A slow, unstable, or unresponsive website not only hurts your organic SEO, but also your advertising efforts, conversion rate, and perceived brand image.

To learn more about the importance of technical SEO, you can check out our full service here:

https://bofu.ca/pages/seo-technique

Or read our reference article:

https://bofu.ca/blogs/le-haut-de-l-entonnoir/seo-technique

LCP: Main Content Loading Speed

LCP measures the time it takes to display the largest visible element on the page. This is often a large image, a carousel, a block of text, or a video.

A poor LCP score is usually caused by uncompressed images, render-blocking CSS, poorly optimized JavaScript, or slow hosting.

To identify these issues, use tools like PageSpeed Insights, Lighthouse, or Google Search Console (Web Vitals report).

To improve the LCP:

• Use modern image formats like WebP

• Implement lazy loading for non-essential elements

• Preload important resources with the <link rel="preload"> tag

• Use a CDN to distribute your resources

• Minify and bundle CSS and JS files

INP: Responsiveness to user interaction

INP replaces FID (First Input Delay) and better reflects the reality of an interactive site. It measures the time required between a user's interaction and the moment the interface reacts visually.

Poor responsiveness can come from heavy JavaScript, unoptimized marketing pixels, dynamic forms, or poorly managed animations.

Tools like Chrome DevTools, the Web Vitals extension, and Google Search Console can help analyze this behavior.

To optimize the INP:

• Reduce the size of your JavaScript files

• Delay loading of non-essential scripts until after interaction

• Avoid complex animations that block the main thread

• Add immediate visual feedback after click (loader, animation, quick transition)

CLS: Visual stability of your site

CLS measures unexpected layout changes during loading. This often happens when content is inserted without the space being reserved in advance.

This issue is particularly annoying on mobile and can ruin the user experience, in addition to lowering your site's overall rating.

The main causes are: images without defined dimensions, fonts that load slowly, or dynamic content (advertising, pop-ups, suggestion modules) injected without a placeholder.

To correct the CLS:

• Always set the dimensions of images and videos in the code

• Use font-display:swap to avoid text flashes

• Reserve space for dynamic modules before they are visible

• Never move an existing element without a smooth transition

Why Marketing Teams Need to Care About Performance

Core Web Vitals are more than just a technical requirement. They have a direct impact on your marketing results:

• A better LCP decreases the bounce rate of your campaign pages

• A good INP makes the experience smoother and improves conversion rates

• A good CLS strengthens the perceived credibility of your site with visitors

By combining good content, an effective advertising strategy and a fast site, you maximize your return on investment.

What you can do right now

• Test your key pages with PageSpeed Insights

• Analyze Vital Web Signals in Google Search Console

• Optimize or remove non-essential third-party integrations

• Improve your images and simplify your scripts

• Request a performance audit from our team

Conclusion

A successful website isn't just about its appearance or content. It must also provide a smooth, fast, and stable experience. Core Web Vitals are the intersection of web development and performance marketing.

To help you improve these indicators and optimize your digital strategy, our team can support you.

Discover our technical SEO services or contact us directly.