Core Web Vitals on SEO: In 2021, Google introduced Core Web Vitals as official SEO ranking factor. These metrics measure the user experience (UX) of a website and have a direct impact on positioning in search results.
Today, in 2025, Google’s algorithm is even more demanding, favoring fast, stable and responsive sites.
π Core Web Vitals on SEO Why is it important?
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Google favors sites offering a good user experience
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A slow or unstable site suffers a drop in ranking and traffic
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Improving your Core Web Vitals boosts the conversion rate and reduces the bounce rate
In this article, we will analyze in depth the Core Web Vitals, their impact on SEO, and especially how to optimize your site to stay competitive in 2025. π
Understanding Core Web Vitals: The 3 Key Factors
The Core Web Vitals are based on 3 major indicators, each measuring an essential aspect of UX:
1. LCP (Largest Contentful Paint) β Loading Speed
π What is it?
LCP measures the time it takes to load the main element of a page (e.g. an image or a block of text).
π Impact on SEO:
- A LCP that is too long (> 2.5s) leads to a degradation of Google ranking
- A fast site improves the user experience and reduces the bounce rate
π§ How to optimize?
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Optimize images (WebP, compression)
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Use good hosting and a CDN
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Enable caching and lazy loading
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Minify CSS and JavaScript
2. FID (First Input Delay) β Interactivity
π What is it?
The FID measures the response time of a page after the first user interaction (click, scroll, etc.).
π Impact on SEO:
- A high FID (> 100 ms) gives the impression of a slow site
- Google penalizes unresponsive pages
π§ How to optimize?
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Reduce blocking JavaScript (async, defer)
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Use a CDN to load resources faster
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Limit third-party scripts and heavy ads
3. CLS (Cumulative Layout Shift) β Visual Stability
π What is it?
CLS measures the stability of a page while it is loading. A high score means that elements are moving during rendering, which is detrimental to the user experience.
π Impact on SEO:
- A High CLS (> 0.1) can cause SEO penalties
- Unstable sites frustrate visitors
π§ How to optimize?
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Specify the size of images and videos (width & height)
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Avoid intrusive ads that move content
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Optimize fonts (font-display: swap)
The Impact of Core Web Vitals on Google Ranking
Since their integration into the ranking algorithm, Core Web Vitals directly influence SEO.
π The consequences of a bad Core Web Vitals score:
β Drop in Google ranking π
β High bounce rate π
β Fewer conversions and sales πΈ
β Bad user experience π‘
π The benefits of a good Core Web Vitals score:
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Improved SEO ranking π
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More organic traffic π
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Better conversion rate π°
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Optimal user experience π
π’ Example: In 2022, Google found that a site with an optimized LCP has a 24% greater chance of being on the 1st page!
How to Improve your Core Web Vitals in 2025?
π 1. Optimize Loading Speed ββ(LCP)
- Use WebP images and compress them
- Set up a CDN (Cloudflare, BunnyCDN, etc.)
- Reduce the weight of HTML, CSS, and JavaScript
- Enable caching with WP Rocket or LiteSpeed ββCache
β‘ 2. Reduce Response Time (FID)
- Delay loading of heavy scripts (e.g. Google Analytics, ads)
- Use high-performance servers with HTTP/3 and TLS 1.3
- Limit the use of unnecessary JavaScript
π―3. Stabilize the Layout (CLS)
- Reserve spaces for images and videos
- Do not load dynamic content without a defined height
- Avoid pop-ups that change the layout
Tools to Analyze and Improve Your Core Web Vitals
π Recommended tools:
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Google PageSpeed ββInsights β SEO Performance Analysis
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Google Search Console β Core Web Vitals Monitoring
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GTmetrix β Complete Load Time Audit
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Lighthouse β Chromeβs built-in performance optimization tool
π Tip: Regularly monitor your Core Web Vitals report in Google Search Console!
The Importance of Core Web Vitals for SEO in 2025
π’ Why adapt now?
πΉ Google favors ultra-fast sites
πΉ Users leave a site if it takes longer than 3 seconds to load
πΉ speed and UX directly impact conversions
π Concrete example: Amazon calculated that one second delay on its site makes them lose 1.6 billion dollars per year in sales! π±
π Conclusion: Optimizing your Core Web Vitals is a double benefit:
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Better positioning on Google
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Improve user experience and conversions
Conclusion: Adopt Core Web Vitals Best Practices Today!
π Checklist for good SEO in 2025:
β Improve site speed (LCP)
β Reduce response times (FID)
β Stabilize page display (CLS)
β Track your performance with Google Search Console
π A Core Web Vitals optimized site is a site that ranks better and converts more!