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

Audit breakdown by category with detailed findings.

62

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.

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.

RequestCache TTLTransfer Size
www.kobo.com/assets/cross-platform-hero-banner.png14400.0 s160.6 KiB
www.kobo.com/assets/device-images/kobo-clara-colour.webp14400.0 s114.8 KiB
/book-images/b85664f1-c789-4d51-8453-5309298d0dff/200/300...14400.0 s47.0 KiB
/book-images/0a590c27-ccd2-42dd-ad49-c62068a9847b/200/300...14400.0 s33.7 KiB
/book-images/be04ac0d-6546-478c-bed8-06e5861f1b57/200/300...14400.0 s31.9 KiB
/book-images/9f05c3e7-426c-4bae-8254-9e7f32df1c29/200/300...14400.0 s26.5 KiB
/book-images/7954ecda-3793-4657-82ec-dc9dbbca7db8/200/300...14400.0 s25.6 KiB
/book-images/e15ef203-d9b9-4c12-bec2-f8b0dc7e2ec4/200/300...14400.0 s24.8 KiB
/book-images/82abdf24-97c5-4116-a02d-4fb0e80a067b/200/300...14400.0 s23.2 KiB
/book-images/0e717cc9-16ce-4a58-ac69-70bf10f998cf/200/300...14400.0 s22.1 KiB
/book-images/2941dfd1-c3c8-45f0-9e1c-0f278b5a4a60/200/300...14400.0 s21.3 KiB
www.kobo.com/assets/device-images/kobo-clara-bw.webp14400.0 s21.2 KiB
/book-images/2bac25ea-8dac-494d-8758-1e950a77d1ec/200/300...14400.0 s21.1 KiB
/book-images/fe24a2e8-3085-47e2-b304-1f4a10dd51dd/200/300...14400.0 s20.7 KiB
/book-images/b486fd0b-d90d-460d-85f4-c7ac277b44c6/200/300...14400.0 s20.5 KiB
/book-images/f205ffe8-1f3f-47a5-9d24-787fd6ed6a26/200/300...14400.0 s20.4 KiB
/book-images/ac422f29-b049-49c4-b4a1-05729bf9897e/200/300...14400.0 s20.0 KiB
/book-images/7370b593-54b3-4e23-9353-1d2a01b8fa46/200/300...14400.0 s18.7 KiB
/book-images/45f5f7fe-8213-4801-ab46-519380049919/200/300...14400.0 s16.9 KiB
/book-images/e9789b8c-7c73-4025-8fdb-379b6b57c02a/200/300...14400.0 s16.5 KiB
/book-images/c9f113c7-9ad3-4a42-87cf-545fa615dbdb/200/300...14400.0 s16.1 KiB
/book-images/66a87a88-1d17-45ab-afe2-4137273c6087/200/300...14400.0 s15.8 KiB
/book-images/0373966b-452e-4870-8760-7248eb8ccfd8/200/300...14400.0 s15.6 KiB
www.kobo.com/assets/device-images/kobo-elipsa-2e.webp14400.0 s15.3 KiB
/book-images/0f2eb19c-8272-43b0-a526-8d0f0a020a43/200/300...14400.0 s15.1 KiB
/book-images/93488a68-41df-4d15-af20-5a70aec08ffe/200/300...14400.0 s13.9 KiB
/book-images/814f9752-c151-4183-b20f-7039420da8e6/200/300...14400.0 s13.7 KiB
/book-images/ec8be67d-0ee4-42f1-8bf3-83e7b36e1b18/200/300...14400.0 s13.4 KiB
/book-images/b4df0d04-1a44-46b9-9604-2753aa27372d/200/300...14400.0 s13.2 KiB
/book-images/558994bd-4c4c-4e32-b132-64e09e7f6a0a/200/300...14400.0 s12.9 KiB
www.kobo.com/assets/device-images/kobo-sage.webp14400.0 s12.3 KiB
www.kobo.com/assets/device-images/kobo-libra-colour.webp14400.0 s11.9 KiB
/book-images/d1ff55f3-2fd2-47d4-ba00-c5c6e90a2b4c/200/300...14400.0 s10.3 KiB
/book-images/13abc7bd-78d8-407d-91de-465dcefdf60d/200/300...14400.0 s8.8 KiB
cdn.builder.io/api/v1/pixel?apiKey=7835b45c92b04a26beedd3c1851c74a515.0 s1.1 KiB

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:0.260029] map[node:map[boundingRect:map[bottom:0 height:0 left:0 right:0 top:0 width:0] lhId:page-38-DIV nodeLabel:Los mejores libros en EspañaSaltar esta listaTodas las categoríasCiencia ficció… path:2,MAIN,0,DIV,1,DIV,22,DIV selector:main#main > div > div.flex > div.flex snippet:<div data-testid="tab-carousel-section" data-track-info="{&quot;widgetName&quot;:&quot;TabCarousel&quot;,&quot;carouselName&quot;:&quot;Los mejores libros en España&quot;}" class="flex flex-col flex-wrap w-full relative gap-medium" data-rac="" data-orientation="horizontal"> type:node] score:0.244665] map[node:map[boundingRect:map[bottom:0 height:0 left:0 right:0 top:0 width:0] lhId:page-34-DIV nodeLabel:Tu configuración de privacidadAl seleccionar "Aceptar todas", permites que Raku… path:0,SECTION,1,DIV selector:div > section.fixed > div.flex snippet:<div class="flex items-start self-stretch flex-grow flex-column gap-medium"> type:node] score:0.015279 subItems:map[items:[map[cause:Web font extra:map[type:url value:https://www.kobo.com/_next/static/media/kobo-icon.46e2a41d.ttf]] map[cause:Web font extra:map[type:url value:https://www.kobo.com/_next/static/media/RakutenSans_UI_W_SBd.f0214d36.woff2]]] type:subitems]] map[node:map[boundingRect:map[bottom:0 height:0 left:0 right:0 top:0 width:0] lhId:page-32-DIV nodeLabel:Lista de deseosCestaCrear cuenta¿Tienes cuenta?Iniciar sesión path:1,HEADER,1,DIV,1,DIV,0,DIV,0,DIV,1,DIV selector:div.d-flex > div.sc-a8fa1d0f-0 > div.container > div.d-flex snippet:<div class="d-flex align-items-start gap-2xsmall"> type:node] score:8.5e-05 subItems:map[items:[map[cause:Web font extra:map[type:url value:https://www.kobo.com/_next/static/media/RakutenSans_UI_W_Rg.05377cc8.woff2]] map[cause:Web font extra:map[type:url value:https://www.kobo.com/_next/static/media/RakutenSerif_W_Rg.0ce79e60.woff2]]] type:subitems]]]
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:0.048202] map[node:map[boundingRect:map[bottom:110 height:50 left:353 right:850 top:60 width:497] lhId:page-40-::after nodeLabel:div.sc-c25606a2-1 > div.sc-f0a6fa4c-0 > div.sc-f0a6fa4c-2 > ::after path:1,HTML,1,BODY,137,DIV,1,HEADER,1,DIV,1,DIV,0,DIV,0,DIV,0,DIV,1,DIV,0,FORM,0,DIV,0,DIV,0,DIV,1,DIV,0,::after selector:div.sc-c25606a2-1 > div.sc-f0a6fa4c-0 > div.sc-f0a6fa4c-2 > ::after snippet:<::after> type:node] score:0.048202]]

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.

URLEst Savings
www.kobo.com/_next/static/media/kobo-icon.46e2a41d.ttf55 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:Top function call valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]
items: [map[reflowTime:92.281 source:map[column:44732 line:1 type:source-location url:https://www.kobo.com/_next/static/chunks/90018-47990356ea45b8c5.js urlProvider:network]]]
headings: [map[key:source label:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]
items: [map[reflowTime:27.34 source:map[column:64639 line:0 type:source-location url:https://www.kobo.com/_next/static/chunks/app/%5Bcountry%5D/%5Blanguage%5D/(layout-with-default-header-footer)/layout-01d9ac341846e1d3.js urlProvider:network]] map[reflowTime:8.446 source:map[column:13062 line:6 type:source-location url:https://www.kobo.com/_next/static/chunks/3734-bd688891068e2c01.js urlProvider:network]] map[reflowTime:64.941 source:map[column:16355 line:0 type:source-location url:https://www.kobo.com/_next/static/chunks/41986-fd2f8a20775adabf.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.

URLResource SizeEst Savings
div.builder-blocks > div.builder-971b1a6ddf1c4afb8d9b4d5ea10530d9 > section.w-full > img.w-full div.builder-blocks > div.builder-971b1a6ddf1c4afb8d9b4d5ea10530d9 > section.w-full > img.w-full
/api/v1/image/assets/7835b45c92b04a26beedd3c1851c74a5/b66...159.9 KiB119.1 KiB
div > div.flex > section.w-full > img.w-full div > div.flex > section.w-full > img.w-full
www.kobo.com/assets/cross-platform-hero-banner.png160.3 KiB119.1 KiB
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-clara-colour.webp114.6 KiB104.8 KiB
Oferta especial del día - eBook de Margaret Drabble div.sc-cc2257d9-3 > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/b85664f1-c789-4d51-8453-5309298d0dff/200/300...46.7 KiB36.4 KiB
La comadrona - eBook de Bibbiana Cau div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/0a590c27-ccd2-42dd-ad49-c62068a9847b/200/300...33.6 KiB23.7 KiB
La península de las casas vacías - eBook de David Uclés div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/be04ac0d-6546-478c-bed8-06e5861f1b57/200/300...31.7 KiB21.8 KiB
Novedad recomendada - eBook de J. D. Barker, James Patterson div.sc-cc2257d9-3 > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/9f05c3e7-426c-4bae-8254-9e7f32df1c29/200/300...26.4 KiB16.7 KiB
La muerta enamorada - eBook de Théophile Gautier div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/7954ecda-3793-4657-82ec-dc9dbbca7db8/200/300...25.5 KiB15.9 KiB
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-clara-bw.webp21.2 KiB15.7 KiB
div.builder-blocks > div.builder-7d573b226f7348ecbb099cd3d994ab61 > section.relative > img.transition div.builder-blocks > div.builder-7d573b226f7348ecbb099cd3d994ab61 > section.relative > img.transition
/api/v1/image/assets/7835b45c92b04a26beedd3c1851c74a5/9f9...28.7 KiB15.0 KiB
El monasterio de la rosa negra. Un gran thriller histórico. Un secreto milenari… div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/e15ef203-d9b9-4c12-bec2-f8b0dc7e2ec4/200/300...24.7 KiB14.6 KiB
La obra maestra - eBook de Daniel Silva div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/82abdf24-97c5-4116-a02d-4fb0e80a067b/200/300...23.1 KiB13.5 KiB
La Ronda - eBook de Francisco Bescós div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/0e717cc9-16ce-4a58-ac69-70bf10f998cf/200/300...22.0 KiB12.1 KiB
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-elipsa-2e.webp15.2 KiB11.3 KiB
Resultado final - eBook de Don Winslow div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/fe24a2e8-3085-47e2-b304-1f4a10dd51dd/200/300...20.6 KiB11.1 KiB
La vida al final - eBook de Bernhard Schlink div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/2bac25ea-8dac-494d-8758-1e950a77d1ec/200/300...21.0 KiB10.8 KiB
El amo (Jotadé 2) - eBook de Santiago Díaz div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/2941dfd1-c3c8-45f0-9e1c-0f278b5a4a60/200/300...21.1 KiB10.8 KiB
Querida Debbie - eBook de Freida McFadden div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/b486fd0b-d90d-460d-85f4-c7ac277b44c6/200/300...20.4 KiB10.5 KiB
Dorayaki - eBook de Durian Sukegawa div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/f205ffe8-1f3f-47a5-9d24-787fd6ed6a26/200/300...20.3 KiB10.5 KiB
La villa de las telas (La villa de las telas 1) - eBook de Anne Jacobs div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/ac422f29-b049-49c4-b4a1-05729bf9897e/200/300...19.9 KiB10.0 KiB
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-sage.webp12.2 KiB9.1 KiB
div.builder-blocks > div.builder-d713707e32b54a0691d8423b18f7e492 > section.relative > img.transition div.builder-blocks > div.builder-d713707e32b54a0691d8423b18f7e492 > section.relative > img.transition
/api/v1/image/assets/7835b45c92b04a26beedd3c1851c74a5/4ef...16.9 KiB8.8 KiB
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-libra-colour.webp11.8 KiB8.8 KiB
La niña del tren - eBook de Andrea Mara div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/7370b593-54b3-4e23-9353-1d2a01b8fa46/200/300...18.5 KiB8.3 KiB
El volumen del tiempo III - eBook de Solvej Balle div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/45f5f7fe-8213-4801-ab46-519380049919/200/300...16.8 KiB6.5 KiB
Novedad destacada - eBook de Elísabet Benavent div.sc-cc2257d9-3 > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/e9789b8c-7c73-4025-8fdb-379b6b57c02a/200/300...16.4 KiB6.5 KiB
Asesinato en el Molino del Cura (Los crímenes de Loeiro 2) - eBook de Arantza P… div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/c9f113c7-9ad3-4a42-87cf-545fa615dbdb/200/300...15.9 KiB6.0 KiB
Llevará tu nombre - eBook de Sonsoles Ónega div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/0373966b-452e-4870-8760-7248eb8ccfd8/200/300...15.5 KiB5.6 KiB
Los nueve reinos - eBook de Santiago Díaz div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/66a87a88-1d17-45ab-afe2-4137273c6087/200/300...15.7 KiB5.5 KiB
div.builder-blocks > div.builder-2454f30a7d844a71b2a0171a367ca8f2 > section.relative > img.transition div.builder-blocks > div.builder-2454f30a7d844a71b2a0171a367ca8f2 > section.relative > img.transition
/api/v1/image/assets/7835b45c92b04a26beedd3c1851c74a5/ed6...10.0 KiB5.2 KiB
Ojos de asesina - eBook de Charlie Donlea div.relative > div.sc-f4bb9f6e-1 > picture > img.sc-f4bb9f6e-2
/book-images/0f2eb19c-8272-43b0-a526-8d0f0a020a43/200/300...15.0 KiB5.2 KiB

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

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: 244 ms
URLTime Spent
kobo.com/244 ms
www.kobo.com/0.0 ms

Keep the server response time for the main document short because all other requests depend on it. Learn more about the Time to First Byte metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 622 ms
URLTime Spent
www.kobo.com/722 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.

ElementLayout shift score
Los mejores libros en EspañaSaltar esta listaTodas las categoríasCiencia ficció… main#main > div > div.flex > div.flex
0.245
div.sc-c25606a2-1 > div.sc-f0a6fa4c-0 > div.sc-f0a6fa4c-2 > ::after div.sc-c25606a2-1 > div.sc-f0a6fa4c-0 > div.sc-f0a6fa4c-2 > ::after
0.048
Tu configuración de privacidadAl seleccionar "Aceptar todas", permites que Raku… div > section.fixed > div.flex
0.015
Lista de deseosCestaCrear cuenta¿Tienes cuenta?Iniciar sesión div.d-flex > div.sc-a8fa1d0f-0 > div.container > div.d-flex
0.000

Time to Interactive is the amount of time it takes for the page to become fully interactive. Learn more about the Time to Interactive metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

TTI

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 23.8 KiB
URLTransfer SizeEst Savings
www.kobo.com/_next/static/css/617148611e95c731.css17.2 KiB13.4 KiB
www.kobo.com/_next/static/css/0d2474af8fec3157.css11.2 KiB10.4 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: 90 ms 128.5 KiB
URLTransfer SizeEst Savings
www.kobo.com/_next/static/chunks/77997-911375830be96206.js61.6 KiB58.8 KiB
www.kobo.com/_next/static/chunks/10188-43d379f98b1d35e5.js64.7 KiB48.7 KiB
www.kobo.com/_next/static/chunks/49808-a865af94bb920e07.js31.2 KiB21.1 KiB

Consider reducing the time spent parsing, compiling, and executing JS. You may find delivering smaller JS payloads helps with this. Learn how to reduce Javascript execution time.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLTotal CPU TimeScript EvaluationScript Parse
www.kobo.com/_next/static/chunks/90018-47990356ea45b8c5.js1.3 s1.1 s5.8 ms
www.kobo.com/764 ms43 ms30 ms
Unattributable236 ms14 ms0.0 ms
www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js149 ms37 ms4.9 ms
www.kobo.com/_next/static/chunks/72330-71c1325b9b4a6acd.js79 ms45 ms3.9 ms
/_next/static/chunks/app/[country]/[language]/(layout-wit...74 ms72 ms2.0 ms
www.kobo.com/_next/static/chunks/71749.ef072d46ecd673e6.js73 ms68 ms0.1 ms

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn how to minimize main-thread work

Why this matters

Performance issues directly impact user engagement and conversion rates.

CategoryTime Spent
Script Evaluation1.5 s
Other567 ms
Style & Layout426 ms
Rendering129 ms
Parse HTML & CSS124 ms
Script Parsing & Compilation98 ms
Garbage Collection57 ms

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 reasonFailure type
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

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
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-libra-colour.webp
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-clara-colour.webp
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-clara-bw.webp
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-sage.webp
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-elipsa-2e.webp

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

●Optimize DOM size
●LCP breakdown
●LCP request discovery
●Modern HTTP
●Render blocking requests
●Optimize viewport for mobile
●Minify CSS
●Minify JavaScript
●Avoids enormous network payloads Total size was 2,513 KiB
●Avoid long main-thread tasks 9 long tasks found
●Avoid non-composited animations 57 animated elements found
●Network Requests
●Network Round Trip Times 50 ms
●Server Backend Latencies 140 ms
●Tasks
●Diagnostics
●Metrics
●Screenshot Thumbnails
●Final Screenshot
●Script Treemap Data
●Resources Summary
○INP breakdown
○User Timing marks and measures
100

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.

Visible text labels that do not match the accessible name can result in a confusing experience for screen reader users. Learn more about accessible names.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Cesta div.sc-a8fa1d0f-0 > div.container > div.d-flex > a.sc-a8fa1d0f-2
○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>`
●`[role]`s have all required `[aria-*]` attributes
●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
●`[role]` values are valid
●`[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.
●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
●`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.
●Definition list items are wrapped in `<dl>` elements
●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
●Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
●List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements
●No element has a `[tabindex]` value greater than 0
●Touch targets have sufficient size and spacing.
●Heading elements appear in a sequentially-descending order
●Document has a main landmark.
●Deprecated ARIA roles were not used
●Uses ARIA roles only on compatible elements
●Image elements do not have `[alt]` attributes that are redundant text.
●Identical links have the same purpose.
○`[accesskey]` values are unique
○`button`, `link`, and `menuitem` elements have accessible names
○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
○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.
○Skip links are focusable.
○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.
○`[lang]` attributes have a valid value
○`<video>` elements contain a `<track>` element with `[kind="captions"]`
○Tables have different content in the summary attribute and `<caption>`.
○All heading elements contain content.
○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.
92

Best Practices

User Experience

Image display dimensions should match natural aspect ratio. Learn more about image aspect ratio.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLAspect Ratio (Displayed)Aspect Ratio (Actual)
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-libra-colour.webp199 x 300 (0.66)388 x 600 (0.65)
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-clara-colour.webp199 x 300 (0.66)388 x 600 (0.65)
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-clara-bw.webp199 x 300 (0.66)388 x 600 (0.65)
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-sage.webp199 x 300 (0.66)388 x 600 (0.65)
section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4 section.sc-344fd8cf-4 > div.relative > div.flex > img.bg-black-4
www.kobo.com/assets/device-images/kobo-elipsa-2e.webp199 x 300 (0.66)388 x 600 (0.65)

General

Errors logged to the console indicate unresolved problems. They can come from network request failures and other browser concerns. Learn more about this errors in console diagnostic audit

Why this matters

Performance issues directly impact user engagement and conversion rates.

SourceDescription
www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js
Error: Minified React error #418; visit https://react.dev/errors/418?args[]=text&args[]= for the full message or use the non-minified dev environment for full errors and additional helpful warnings. at rD (https://www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js:1:35060) at rO (https://www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js:1:36093) at https://www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js:1:118081 at ix (https://www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js:1:122953) at ik (https://www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js:1:114741) at https://www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js:1:110728 at iu (https://www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js:1:110829) at iX (https://www.kobo.com/_next/static/chunks/87c73c54-09e1ba5c70e60a51.js:1:132932) at MessagePort.w (https://www.kobo.com/_next/static/chunks/90018-47990356ea45b8c5.js:1:44971)
●Uses HTTPS
●Avoids deprecated APIs
●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
●Serves images with appropriate resolution
●Page has the HTML doctype
●Properly defines charset
●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 clickjacking with XFO or CSP
●Mitigate DOM-based XSS with Trusted Types
●Detected JavaScript libraries
●Page has valid source maps
○Redirects HTTP traffic to HTTPS
92

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.

Content Best Practices

Canonical links suggest which URL to show in search results. Learn more about canonical links.

Why this matters

Informational: a Permissions-Policy directive showing feature -> allowed origins.

Source: MDN Permissions-Policy

Format your HTML in a way that enables crawlers to better understand your app’s content.

○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`

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