Lighthouse Desktop

· 0 checks — Desktop Lighthouse audit -- Performance, Accessibility, Best Practices, and SEO category breakdown.

SCORE

GRADE

FIX

REVIEW

PASS

INFO

Detailed Report

Audit breakdown by category with detailed findings.

Performance

Insights

Remove large, duplicate JavaScript modules from bundles to reduce unnecessary bytes consumed by network activity.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Polyfills and transforms enable older browsers to use new JavaScript features. However, many aren't necessary for modern browsers. Consider modifying your JavaScript build process to not transpile Baseline features, unless you know you must support older browsers. Learn why most sites can deploy ES6+ code without transpiling

Why this matters

Performance issues directly impact user engagement and conversion rates.

3rd party code can significantly impact load performance. Reduce and defer loading of 3rd party code to prioritize your page's content.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Layout shifts occur when elements move absent any user interaction. Investigate the causes of layout shifts, such as elements being added, removed, or their fonts changing as the page loads.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:node label:Element subItemsHeading:map[key:extra] valueType:node] map[granularity:0.001 key:score label:Layout shift score subItemsHeading:map[key:cause valueType:text] valueType:numeric]]

items: [map[node:map[type:text value:Total] score:0.464229] map[node:map[boundingRect:map[bottom:1761 height:1605 left:0 right:1350 top:156 width:1350] lhId:page-10-MAIN nodeLabel:L’Institut national de la statistique et des études économiques collecte, produ… path:1,HTML,1,BODY,8,MAIN selector:body > main#contenu snippet:<main id="contenu" class="main" role="main"> type:node] score:0.464229 subItems:map[items:[map[cause:Unsized image element extra:map[boundingRect:map[bottom:89 height:75 left:163 right:387 top:14 width:224] lhId:page-15-IMG nodeLabel:Insee - Institut national de la statistique et des études économiques - Mesurer… path:1,HTML,1,BODY,7,HEADER,2,DIV,0,DIV,3,DIV,0,IMG selector:div#banniere > div.bandeau > div#logo > img.logo snippet:<img class="logo logo-accueil lien-logo" src="/static/img/logoInseeFr.svg" height="75px" data-i18n="[alt]header.logo.alt" alt="Insee - Institut national de la statistique et des études économiques - Me…"> type:node]]] type:subitems]]]

Your first network request is the most important. Reduce its latency by avoiding redirects, ensuring a fast server response, and enabling text compression.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Consider setting font-display to swap or optional to ensure text is consistently visible. swap can be further optimized to mitigate layout shifts with font metric overrides.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Est Savings
www.insee.fr/static/fonts/RemixIcon/remixicon.woff2?t=1718271040674	105 ms
www.insee.fr/static/fonts/INSEE_icoFont.woff?7o844o	50 ms

A forced reflow occurs when JavaScript queries geometric properties (such as offsetWidth) after styles have been invalidated by a change to the DOM state. This can result in poor performance. Learn more about forced reflows and possible mitigations.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:source label:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]

items: [map[reflowTime:44.858 source:map[type:text value:[unattributed]]] map[reflowTime:0.634 source:map[column:30422 line:2 type:source-location url:https://www.insee.fr/static/js/application-lib.min.js urlProvider:network]]]

Reducing the download time of images can improve the perceived load time of the page and LCP. Learn more about optimizing image size

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL	Resource Size	Est Savings
Classe prépa Talents `a.section-bandeau > div.section-graphique-bandeau > div.graphique-bandeau > img.image-bandeau`	www.insee.fr/image/actualite/8546313/Bandeau_CPT_inseefr_2026.png	96.4 KiB	82.9 KiB
Hausse des prix de l’essence : les ménages français l’ont anticipée ! `a.section-bandeau > div.section-graphique-bandeau > div.graphique-bandeau > img.image-bandeau`	/image/actualite/8982301/blogInsee_2026_04_hausse_des_pri...	83.0 KiB	69.5 KiB
Avec l'Ensai, devenez datascientist `a.section-bandeau > div.section-graphique-bandeau > div.graphique-bandeau > img.image-bandeau`	www.insee.fr/image/actualite/7724909/Bandeau%20Ensai.png	76.5 KiB	63.0 KiB
Services Publics + `ul.images-footer > li.image-footer > a.lien-footer-image > img`	www.insee.fr/static/img/footer/Service_public.png	45.2 KiB	44.3 KiB
Réseau Quetelet `ul.images-footer > li.image-footer > a.lien-footer-image > img`	www.insee.fr/static/img/footer/Reseau_quetelet.png	8.4 KiB	7.6 KiB
site data.gouv `ul.images-footer > li.image-footer > a.lien-footer-image > img`	www.insee.fr/static/img/footer/data.gouv.png	7.7 KiB	6.9 KiB
div.reseaux-sociaux > div.contenu-reseaux-sociaux > a > img.cercle-instagram `div.reseaux-sociaux > div.contenu-reseaux-sociaux > a > img.cercle-instagram`	www.insee.fr/static/img/logo-instagram-small.png	5.7 KiB	5.4 KiB
La nomenclature d'activités française (NAF) change `a.section-bandeau > div.section-graphique-bandeau > div.graphique-bandeau > img.image-bandeau`	www.insee.fr/image/actualite/8734429/Bandeau%20naf%20vfinale.png	18.4 KiB	4.9 KiB
Système Statistique Européen `ul.images-footer > li.image-footer > a.lien-footer-image > img`	www.insee.fr/static/img/footer/sse.png	5.2 KiB	4.8 KiB

Optimize LCP by making the LCP image discoverable from the HTML immediately, and avoiding lazy-loading

Why this matters

Performance issues directly impact user engagement and conversion rates.

lhId: page-9-IMG

nodeLabel: Hausse des prix de l’essence : les ménages français l’ont anticipée !

path: 1,HTML,1,BODY,8,MAIN,2,DIV,0,DIV,0,DIV,0,SECTION,1,DIV,0,DIV,0,DIV,1,DIV,0,DIV,0,A,0,DIV,0,DIV,0,IMG

selector: a.section-bandeau > div.section-graphique-bandeau > div.graphique-bandeau > img.image-bandeau

snippet: <img alt="Hausse des prix de l’essence : les ménages français l’ont anticipée !" src="/image/actualite/8982301/blogInsee_2026_04_hausse_des_prix_de_l_essence_po…" class="image-bandeau">

Avoid chaining critical requests by reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.

Why this matters

Performance issues directly impact user engagement and conversion rates.

description: [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints help the browser establish a connection earlier in the page load, saving time when the first request for that origin is made. The following are the origins that the page preconnected to.

title: Preconnected origins

value: no origins were preconnected

description: Add [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints to your most important origins, but try to use no more than 4.

title: Preconnect candidates

value: No additional origins are good candidates for preconnecting

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Transfer Size	Duration
www.insee.fr/static/build/highcharts-insee.js	585.5 KiB	480 ms
www.insee.fr/static/build/highcharts.js	322.4 KiB	280 ms
www.insee.fr/static/css/application.css	84.4 KiB	80 ms
www.insee.fr/static/css/swiper/swiper.min.css	3.0 KiB
www.insee.fr/static/css/featherlight/featherlight.css	1.4 KiB
www.insee.fr/static/css/dateTimePicker/jquery.datetimepicker.css	3.9 KiB

A long cache lifetime can speed up repeat visits to your page. Learn more about caching.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Request	Cache TTL	Transfer Size
cdn.matomo.cloud/insee.matomo.cloud/container_j86K86K5.js	691200.0 s	50.3 KiB

These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.

Redirects introduce additional delays before the page can be loaded. Learn how to avoid page redirects.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 484 ms

URL	Time Spent
insee.fr/	252 ms
www.insee.fr/	232 ms
www.insee.fr/fr/accueil	0.0 ms

These are the largest layout shifts observed on the page. Each table item represents a single layout shift, and shows the element that shifted the most. Below each item are possible root causes that led to the layout shift. Some of these layout shifts may not be included in the CLS metric value due to windowing. Learn how to improve CLS

Why this matters

Performance issues directly impact user engagement and conversion rates.

Element	Layout shift score
L’Institut national de la statistique et des études économiques collecte, produ… `body > main#contenu`	0.464

The maximum potential First Input Delay that your users could experience is the duration of the longest task. Learn more about the Maximum Potential First Input Delay metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Diagnostics

Reduce unused rules from stylesheets and defer CSS not used for above-the-fold content to decrease bytes consumed by network activity. Learn how to reduce unused CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 40 ms 73.0 KiB

URL	Transfer Size	Est Savings
www.insee.fr/static/css/application.css	84.2 KiB	73.0 KiB

Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. Learn how to reduce unused JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 820 ms 968.2 KiB

URL	Transfer Size	Est Savings
www.insee.fr/static/build/highcharts-insee.js	576.4 KiB	375.8 KiB
www.insee.fr/static/build/highcharts.js	322.3 KiB	270.8 KiB
www.insee.fr/static/js/application-lib.min.js	258.6 KiB	193.1 KiB
www.insee.fr/static/build/application.js	116.8 KiB	101.4 KiB
cdn.matomo.cloud/insee.matomo.cloud/container_j86K86K5.js	49.8 KiB	27.1 KiB

Many navigations are performed by going back to a previous page, or forwards again. The back/forward cache (bfcache) can speed up these return navigations. Learn more about the bfcache

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failure reason	Failure type
The page has an unload handler in the main frame.	Actionable
Pages with cache-control:no-store header cannot enter back/forward cache.	Actionable
Pages whose main resource has cache-control:no-store cannot enter back/forward cache.	Not actionable
Back/forward cache is disabled because some JavaScript network request received resource with Cache-Control: no-store header.	Not actionable

Minifying JavaScript files can reduce payload sizes and script parse time. Learn how to minify JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 3.2 KiB

URL	Transfer Size	Est Savings
www.insee.fr/static/js/svg/graphsvg.js	10.1 KiB	3.2 KiB

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. Learn how to set image dimensions

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL
Insee - Institut national de la statistique et des études économiques - Mesurer… `div#banniere > div.bandeau > div#logo > img.logo`	www.insee.fr/static/img/logoInseeFr.svg
Services Publics + `ul.images-footer > li.image-footer > a.lien-footer-image > img`	www.insee.fr/static/img/footer/Service_public.png
Accès sourds et malentendants `ul.liste-lien-acces > li > a > img#picto-acceo`	www.insee.fr/static/img/pictooreille.svg
Réseau Quetelet `ul.images-footer > li.image-footer > a.lien-footer-image > img`	www.insee.fr/static/img/footer/Reseau_quetelet.png
site data.gouv `ul.images-footer > li.image-footer > a.lien-footer-image > img`	www.insee.fr/static/img/footer/data.gouv.png
Insee Analyses `div#contenu-section-a-la-une > article.section-actualite > a.lien-fil-actualite > img`	www.insee.fr/static/img/a-la-une/collection.png
Insee Analyses `div#contenu-section-a-la-une > article.section-actualite > a.lien-fil-actualite > img`	www.insee.fr/static/img/a-la-une/collection.png
Insee Focus `div#contenu-section-a-la-une > article.section-actualite > a.lien-fil-actualite > img`	www.insee.fr/fr/statistiques/vignette/8967255/Image_accueil.png
Informations rapides `div#contenu-section-a-la-une > article.section-actualite > a.lien-fil-actualite > img`	www.insee.fr/static/img/a-la-une/conjoncture.png
Centre d'Accès Sécurisé Distant aux données (CASD) `ul.images-footer > li.image-footer > a.lien-footer-image > img`	www.insee.fr/static/img/footer/CASD.png
Système Statistique Européen `ul.images-footer > li.image-footer > a.lien-footer-image > img`	www.insee.fr/static/img/footer/sse.png

More information about the performance of your application. These numbers don't directly affect the Performance score.

●Time to Interactive 2.1 s

●Optimize DOM size

●LCP breakdown

●Modern HTTP

●Optimize viewport for mobile

●Minify CSS

●Avoids enormous network payloads Total size was 2,235 KiB

●JavaScript execution time 0.3 s

●Minimizes main-thread work 0.6 s

●Avoid long main-thread tasks 2 long tasks found

●Network Requests

●Network Round Trip Times 30 ms

●Server Backend Latencies 60 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Initial server response time was short Root document took 50 ms

○INP breakdown

○User Timing marks and measures

○Avoid non-composited animations

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

ARIA

Some ARIA roles have required attributes that describe the state of the element to screen readers. Learn more about roles and required attributes.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Lancer la recherche sur le site Thèmes `div#banniere > div.bandeau > div#recherche-header > div#searchbar-header`

ARIA roles must have valid values in order to perform their intended accessibility functions. Learn more about valid ARIA roles.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
L’Institut national de la statistique et des études économiques collecte, produ… `body > main#contenu > div.breadcrum`

These are opportunities to improve the usage of ARIA in your application which may enhance the experience for users of assistive technology, like a screen reader.

Tables and lists

Screen readers have a specific way of announcing lists. Ensuring proper list structure aids screen reader output. Learn more about proper list structure.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
STATISTIQUES ET ÉTUDES DÉFINITIONS, MÉTHODES ET QUALITÉ Définitions Sources sta… `div.footer > div.container-bloc-2 > div.bloc-2 > ul`

Screen readers require list items (`<li>`) to be contained within a parent `<ul>`, `<ol>` or `<menu>` to be announced properly. Learn more about proper list structure.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
STATISTIQUES ET ÉTUDES `div.bloc-2 > ul > div.colonne-1 > li.liste-niveau-1`
DÉFINITIONS, MÉTHODES ET QUALITÉ Définitions Sources statistiques et indicateur… `div.bloc-2 > ul > div.colonne-1 > li.liste-niveau-1`
SERVICES Réviser une pension, un loyer, bail ou contrat Consulter les indices e… `div.bloc-2 > ul > div.colonne-2 > li.liste-niveau-1`
L'INSEE ET LA STATISTIQUE PUBLIQUE L'Insee Les activités de l'Insee La statisti… `div.bloc-2 > ul > div.colonne-2 > li.liste-niveau-1`

These are opportunities to improve the experience of reading tabular or list data using assistive technology, like a screen reader.

○Interactive controls are keyboard focusable

○Interactive elements indicate their purpose and state

○The page has a logical tab order

○Visual order on the page follows DOM order

○User focus is not accidentally trapped in a region

○The user's focus is directed to new content added to the page

○HTML5 landmark elements are used to improve navigation

○Offscreen content is hidden from assistive technology

○Custom controls have associated labels

○Custom controls have ARIA roles

●`[aria-*]` attributes match their roles

●`[aria-hidden="true"]` is not present on the document `<body>`

●Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.

●`[role]`s are contained by their required parent element

●`[aria-*]` attributes have valid values

●`[aria-*]` attributes are valid and not misspelled

●Buttons have an accessible name

●Image elements have `[alt]` attributes

●Form elements have associated labels

●`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.

●`button`, `link`, and `menuitem` elements have accessible names

●ARIA attributes are used as specified for the element's role

●`[aria-hidden="true"]` elements do not contain focusable descendents

●Elements use only permitted ARIA attributes

●Background and foreground colors have a sufficient contrast ratio

●Document has a `<title>` element

●`<html>` element has a `[lang]` attribute

●`<html>` element has a valid value for its `[lang]` attribute

●Links have a discernible name

●No element has a `[tabindex]` value greater than 0

●Touch targets have sufficient size and spacing.

●`[lang]` attributes have a valid value

●Heading elements appear in a sequentially-descending order

●Skip links are focusable.

●Document has a main landmark.

●Deprecated ARIA roles were not used

●Uses ARIA roles only on compatible elements

○`[accesskey]` values are unique

○Elements with `role="dialog"` or `role="alertdialog"` have accessible names.

○ARIA input fields have accessible names

○ARIA `meter` elements have accessible names

○ARIA `progressbar` elements have accessible names

○Elements with the `role=text` attribute do not have focusable descendents.

○ARIA toggle fields have accessible names

○ARIA `tooltip` elements have accessible names

○ARIA `treeitem` elements have accessible names

○The page contains a heading, skip link, or landmark region

○`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.

○Definition list items are wrapped in `<dl>` elements

○ARIA IDs are unique

○No form fields have multiple labels

○`<frame>` or `<iframe>` elements have a title

○`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.

○Input buttons have discernible text.

○`<input type="image">` elements have `[alt]` text

○Links are distinguishable without relying on color.

○The document does not use `<meta http-equiv="refresh">`

○`<object>` elements have alternate text

○Select elements have associated label elements.

○Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.

○`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.

○`<video>` elements contain a `<track>` element with `[kind="captions"]`

○Tables have different content in the summary attribute and `<caption>`.

○All heading elements contain content.

○Image elements do not have `[alt]` attributes that are redundant text.

○Identical links have the same purpose.

○Elements with visible text labels have matching accessible names.

○Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.

○`<td>` elements in a large `<table>` have one or more table headers.

Best Practices

General

Deprecated APIs will eventually be removed from the browser. Learn more about deprecated APIs.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Deprecation / Warning	Source
Unload event listeners are deprecated and will be removed.	www.insee.fr/static/js/application-lib.min.js line 1, col 14831

Source maps translate minified code to the original source code. This helps developers debug in production. In addition, Lighthouse is able to provide further insights. Consider deploying source maps to take advantage of these benefits. Learn more about source maps.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL
www.insee.fr/static/js/application-lib.min.js
www.insee.fr/static/build/highcharts.js
www.insee.fr/static/build/highcharts-insee.js

●Uses HTTPS

●Avoids third-party cookies

●Allows users to paste into input fields

●Avoids requesting the geolocation permission on page load

●Avoids requesting the notification permission on page load

●Displays images with correct aspect ratio

●Serves images with appropriate resolution

●Page has the HTML doctype

●Properly defines charset

●No browser errors logged to the console

●No issues in the `Issues` panel in Chrome Devtools

●Ensure CSP is effective against XSS attacks

●Use a strong HSTS policy

●Ensure proper origin isolation with COOP

●Mitigate DOM-based XSS with Trusted Types

●Detected JavaScript libraries

○Redirects HTTP traffic to HTTPS

○Mitigate clickjacking with XFO or CSP

100

SEO

These checks ensure that your page is following basic search engine optimization advice. There are many additional factors Lighthouse does not score here that may affect your search ranking, including performance on Core Web Vitals. Learn more about Google Search Essentials.

○Structured data is valid

●Page isn’t blocked from indexing

●Document has a `<title>` element

●Document has a meta description

●Page has successful HTTP status code

●Links have descriptive text

●Links are crawlable

●robots.txt is valid

●Image elements have `[alt]` attributes

●Document has a valid `hreflang`

○Document has a valid `rel=canonical`