Official statement
Other statements from this video 28 ▾
- □ Pourquoi le trafic n'est-il pas un facteur de classement dans Google ?
- □ Faut-il vraiment mettre tous vos liens d'affiliation en nofollow ?
- □ Le JavaScript est-il vraiment compatible avec le SEO ?
- □ Faut-il vraiment éviter les redirections progressives pour préserver son SEO ?
- □ Peut-on vraiment déployer des milliers de redirections 301 sans risque SEO ?
- □ Pourquoi Googlebot ignore-t-il vos boutons 'Charger plus' et comment y remédier ?
- □ Pourquoi les pages orphelines tuent-elles votre SEO même indexées ?
- □ Faut-il arrêter de nofollow les pages About et Contact ?
- □ Les pop-ups bloquants peuvent-ils vraiment compromettre votre indexation Google ?
- □ Pourquoi votre contenu géolocalisé risque-t-il de disparaître de l'index Google ?
- □ Faut-il abandonner le dynamic rendering pour Googlebot ?
- □ L'index Google a-t-il vraiment une limite — et que faire quand vos pages disparaissent ?
- □ Faut-il vraiment vérifier tous vos domaines redirigés dans Search Console ?
- □ Comment Google pondère-t-il ses signaux de ranking via le machine learning ?
- □ Pourquoi votre site a-t-il disparu brutalement de l'index Google ?
- □ Les avertissements de sécurité dans Search Console affectent-ils vraiment vos rankings SEO ?
- □ Les liens affiliés avec redirections 302 posent-ils un problème de cloaking pour Google ?
- □ Les Core Web Vitals d'AMP passent-ils par le cache Google ou votre serveur d'origine ?
- □ Pourquoi Search Console n'affiche-t-il aucune donnée Core Web Vitals pour votre site ?
- □ Le trafic est-il vraiment sans impact sur le classement Google ?
- □ Le JavaScript pour la navigation et le contenu nuit-il vraiment au SEO ?
- □ Faut-il vraiment s'inquiéter du nombre de redirections 301 lors d'une refonte de site ?
- □ Pourquoi les redirections en chaîne sabotent-elles vos restructurations de site ?
- □ Le lazy loading est-il vraiment compatible avec l'indexation Google ?
- □ Google crawle-t-il vraiment votre site uniquement depuis les États-Unis ?
- □ Faut-il abandonner le dynamic rendering pour l'indexation Google ?
- □ Pourquoi les pages orphelines détectées uniquement via sitemap perdent-elles tout leur poids SEO ?
- □ Les pop-ups partiels peuvent-ils ruiner votre SEO autant que les interstitiels plein écran ?
Google assesses Core Web Vitals based on real user experiences, not lab tests. If you serve AMP pages via the official cache, it's the cache performance that will be measured — not your origin server. For sites with and without AMP, field data (CrUX) outweighs any synthetic score. Therefore, your optimization strategy should focus on what your visitors actually see, not what your diagnostic tools indicate.
What you need to understand
What’s the difference between field data and lab data? <\/h3>
Lab data <\/strong> (Lighthouse, PageSpeed Insights in simulation mode) measures performance in a controlled environment: stable connection, standardized hardware, empty cache. Useful for identifying issues, but they do not reflect the reality of your visitors.<\/p> Field data <\/strong> (Chrome User Experience Report or CrUX) aggregates metrics collected from millions of real Chrome users, with their slow connections, old smartphones, and browser extensions. This is what Google uses to evaluate your Core Web Vitals in production — and therefore for ranking.<\/p> When your AMP pages are served through Google's AMP cache <\/strong>, it’s the cached URL that is measured in CrUX — not your original domain. The AMP cache heavily optimizes loading (prerendering, preconnection, aggressive compression), resulting in excellent CWV scores.<\/p> But beware: if your AMP pages are invalid or served directly from your server, they do not go through the cache. In this case, your infrastructure will be measured <\/strong>, with all its potential flaws. Strict AMP validation thus becomes a prerequisite to benefit from this acceleration.<\/p> The CrUX report aggregates metrics from Chrome users who have opted in for usage statistics sharing <\/strong>. Only pages with sufficient traffic volume appear in CrUX — about 28 days of rolling data.<\/p> If your site lacks Chrome traffic, Google may resort to domain-level data <\/strong> (aggregation of all pages) or may not have any data at all. In this latter case, your CWV will technically not be considered for ranking, but you also lose the competitive advantage associated with an optimized experience.<\/p>Why is there a focus on AMP pages and caching? <\/h3>
How does Google collect this real user data? <\/h3>
SEO Expert opinion
Is this statement consistent with observed practices? <\/h3>
Yes, and it confirms what many field experts have found: clients obsessed with their Lighthouse scores of 100/100 do not always see ranking gains, while those optimizing for CrUX move ahead <\/strong>. The AMP nuance is also consistent — we regularly see AMP sites with excellent CWV due to caching but catastrophic performance on canonical versions.<\/p> The problem is that this statement remains deliberately vague about the exact thresholds <\/strong>. Google talks about ‘good,’ ‘needs improvement,’ ‘poor,’ but the boundaries shift. The current 75th percentiles (LCP < 2.5s, FID < 100ms, CLS < 0.1) are recommendations, not guarantees. [To verify] <\/strong>: the real impact of each metric on ranking remains opaque.<\/p> Serving via the AMP cache means delegating performance to Google <\/strong>. You gain speed, but lose control: it’s impossible to inject third-party JavaScript, finely customize the experience, or track with your usual tools. For an e-commerce or SaaS site, this is often a dealbreaker.<\/p> Another point: if Google decides one day to deprioritize AMP <\/strong> (which it has already done by removing the lightning badge from mobile results), you find yourself with an entire technical stack to maintain for uncertain benefits. The cache improves CWV, but does not compensate for weak content or a shaky SEO architecture.<\/p> If your site has not enough Chrome traffic <\/h3>, CrUX has no data about you. Google then falls back on domain-level aggregated data, or may have nothing at all. In this case, your CWV simply do not count — you are evaluated on other criteria (content, backlinks, freshness).<\/p> Another edge case: pages behind a login or paywall <\/h3>. CrUX only collects public pages accessible to Chrome. If a significant part of your site is private, your measured CWV reflect only a fraction of the actual experience. And for multilingual or multi-country sites, CrUX sometimes poorly aggregates data — a fast page in France may be slow in Brazil, but Google does not always distinguish fine enough.<\/p>What nuances need to be addressed regarding AMP caching? <\/h3>
In what cases does this rule not really apply? <\/h3>
Practical impact and recommendations
What concrete steps should be taken to optimize field CWV? <\/h3>
Forget the obsession with a perfect Lighthouse score. Focus on PageSpeed Insights under the “Field Data” tab <\/h3>: this is where you see your real CrUX CWV. If you are in the green (good) for all three metrics at the 75th percentile, you’re good. If you’re orange or red, prioritize actions that affect real user perception <\/h3>.
For AMP, validate each page with the official validator before publication. A minor error (missing attribute, prohibited tag) is enough to block the cache. Use Google Search Console’s AMP Test Tools <\/h3> to check if your pages are eligible for the cache. If they are, monitor the CWV on the cached URL, not on your original domain.<\/p> Do not rely on lab tests to predict your CrUX results. A Lighthouse score of 95 guarantees nothing if your real users have 3G connections and entry-level smartphones. Test on real devices <\/h3>, with network throttling, to approximate field conditions. Another trap: only optimizing the homepage. CrUX evaluates all pages with traffic <\/h3>. If your product pages or blog articles are slow, they drag down your overall metrics. Prioritize high-traffic templates, not just the homepage.<\/p> In Google Search Console, section Experience <\/h3>, check that your AMP pages are listed as ‘valid.’ Then, in PageSpeed Insights, test the AMP cache URL (format Also use the AMP Cache Viewer <\/h3> to inspect what Google is actually serving. Sometimes, a page seems valid but is not cached for obscure reasons (misconfigured HTTP headers, blocking robots.txt). In this case, field CWV will not benefit from any acceleration.<\/p>What mistakes should be avoided when trying to improve CWV? <\/h3>
How can I check if my site is benefiting from the AMP cache? <\/h3>
https://cdn.ampproject.org/c/s/yourdomain.com/page <\/h3>) to see the measured CWV. If scores are excellent on the cache but mediocre on your domain, it means the cache is doing its job.<\/p>
❓ Frequently Asked Questions
Si mes scores Lighthouse sont parfaits mais CrUX médiocre, quel impact sur le ranking ?
Mes pages AMP sont valides mais pas dans le cache — pourquoi ?
Mon site a peu de trafic et pas de données CrUX — les CWV comptent-ils quand même ?
Les CWV mesurés sur mobile et desktop sont-ils pondérés différemment ?
Peut-on améliorer CrUX sans toucher au code, juste avec un CDN ou le cache AMP ?
🎥 From the same video 28
Other SEO insights extracted from this same Google Search Central video · published on 07/05/2021
🎥 Watch the full video on YouTube →Related statements
Get real-time analysis of the latest Google SEO declarations
Be the first to know every time a new official Google statement drops — with full expert analysis.
💬 Comments (0)
Be the first to comment.