G1 — Chapter 7 - Technical SEO

Criterion G1 : Core Web Vitals - LCP — guide + checklist

PART 1 - Fundamentals Chapter 7 - Technical SEO Keyword : core web vitals - lcp

Here we talk about a criterion that often makes the difference in an audit.

The criterion **G1 — Core Web Vitals - LCP** is part of our SEO checklist (335 criteria). Here, you have a **practical** method to check and fix it — with a concrete example.

What exactly this criterion covers

Here we talk about a criterion that often makes the difference in an audit.

**G1 — Core Web Vitals - LCP** (Chapter 7 - Technical SEO): Largest Contentful Paint < 2.5 seconds, optimize images and server

Why it matters (SEO + UX)

Why it matters: it is a technical quality factor (crawl, rendering, indexing). When poorly applied, we often observe: ambiguity (wrong associated query), duplication between pages, or loss of performance on Core Web Vitals.

On volume-generated sites, this criterion also serves as a **safeguard**: a stable rule prevents 1,000 errors at once.

How to check (step by step)

Approach: express audit (manual + 1 tool). Recommended tool: **WebPageTest**.

  1. Open the page in Chrome → DevTools → Performance/Network tab.
  2. Run PageSpeed Insights and note the main weak point.
  3. Check if the problem repeats on mass-generated pages.

Tip: first isolate 10 “representative” URLs (top pages + generated pages) before scaling the fix.

How to fix properly

Strategy: fix + add a safeguard for bulk import.

  • Fix the biggest cost source (images, JS, fonts, cache).
  • Retest, then apply to the template (not page by page).
  • Add a safeguard: weight budget (KB) and CI check if possible.

Then: re-crawl 50–200 URLs, then monitor Search Console for 7–14 days (impressions/CTR/indexing).

Concrete example (illustrative)

Example (illustrative):

  • **Context**: service landing page for restaurant in Nice
  • **Before**: Lighthouse: 56/100 (heavy JS, unoptimized images).
  • **After**: Lighthouse: 77/100 (lazy-load, compression, cache).
  • **Note**: Goal: stabilize CLS.

Checklist to tick

  • [ ] Measure before/after
  • [ ] Respects: optimize images and server
  • [ ] Improvement on template
  • [ ] No CWV regression
  • [ ] Cache and compression OK
FAQ

Frequently asked questions — G1

What is the most common mistake on “Core Web Vitals - LCP”?

Applying an automatic pattern too generic (same logic on all pages) without adding a differentiating element.

What tool is the fastest to check at scale?

For this type of criterion, a crawl (e.g. Screaming Frog) + targeted verification in WebPageTest is generally the fastest combo.

How to prevent this from recurring on 10K generated pages?

Freeze an auto-generation rule (title/structure/schema/URLs) + add automatic control (crawl or test) before production import.

Ready to go from theory to action?

Validate this criterion with an audit, then deepen the method in the Academy.

Audit with the tool → Learn in the Academy →