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Lighthouse Desktop

· 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.

72

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.

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.

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
Blossom Weekend at Ardress House, County Armagh, Northern Ireland.jpg section.sc-oeuc6o-5 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/library/campai...190.0 KiB72.2 KiB
Dog walking in bluebell woodland at Hatchlands Park, Surrey div.sc-1xa2s2r-4 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/library/visit/...92.9 KiB57.6 KiB
A family of four walking across the grass parkland at Knole in Kent looking for… div.sc-1xa2s2r-4 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/regions/kent/p...58.7 KiB23.4 KiB
A group of volunteers picks up litter from the beach at Penrose, Cornwall section.sc-oeuc6o-5 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/regions/cornwa...128.3 KiB16.2 KiB
Visitors walking in bluebell woodland at Hatchlands Park, Surrey div.sc-1xa2s2r-4 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/regions/surrey...21.4 KiB13.3 KiB
A woman taking photographs of the blossom at Beningbrough Hall, North Yorkshire div.sc-1xa2s2r-4 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/regions/yorksh...17.3 KiB9.2 KiB
Three women, dressed as blossom fairies stand underneath cherry blossom div.sc-1xa2s2r-4 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/library/visit/...16.2 KiB8.2 KiB
Two visitors are looking up at an enormous, highly decorated marble fireplace i… div.sc-1xa2s2r-4 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/regions/north-...15.8 KiB7.7 KiB
Aerial view of earthworks in the landscape at Whitesheet Hill, Wiltshire div.sc-1xa2s2r-4 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/regions/wiltsh...15.7 KiB7.7 KiB
Visitor in the bedroom at Paycocke's House and Garden, Essex div.sc-1xa2s2r-4 > figure.sc-17lph2-3 > picture > img
/binaries/content/gallery/website/national/regions/essex-...42.9 KiB7.6 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-0-IMG
nodeLabel: Blossom Weekend at Ardress House, County Armagh, Northern Ireland.jpg
path: 1,HTML,1,BODY,0,DIV,3,DIV,0,DIV,0,MAIN,1,SECTION,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,DIV,0,SECTION,0,FIGURE,0,PICTURE,4,IMG
selector: section.sc-oeuc6o-5 > figure.sc-17lph2-3 > picture > img
snippet: <img src="https://nt.global.ssl.fastly.net/binaries/content/gallery/website/national…" alt="Blossom Weekend at Ardress House, County Armagh, Northern Ireland.jpg">

HTTP/2 and HTTP/3 offer many benefits over HTTP/1.1, such as multiplexing. Learn more about using modern HTTP.

Why this matters

Performance issues directly impact user engagement and conversion rates.

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
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.

URLTransfer SizeDuration
tms.nationaltrust.org.uk/nationaltrust/prod/Bootstrap.js129.7 KiB505 ms

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: 301 ms

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.

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

Diagnostics

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.

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

Minifying CSS files can reduce network payload sizes. Learn how to minify CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 2.1 KiB

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

Layout shift culprits
Optimize DOM size
Font display
Forced reflow
LCP breakdown
Optimize viewport for mobile
Minify JavaScript
Reduce unused CSS
User Timing marks and measures 4 user timings
JavaScript execution time 0.6 s
Minimizes main-thread work 0.9 s
Avoid long main-thread tasks 2 long tasks found
Image elements have explicit `width` and `height`
Network Requests
Network Round Trip Times 30 ms
Server Backend Latencies 310 ms
Tasks
Diagnostics
Metrics
Screenshot Thumbnails
Final Screenshot
Script Treemap Data
Resources Summary
Initial server response time was short Root document took 420 ms
Avoid large layout shifts 2 layout shifts found
INP breakdown
Avoid non-composited animations
93

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

Each ARIA `role` supports a specific subset of `aria-*` attributes. Mismatching these invalidates the `aria-*` attributes. Learn how to match ARIA attributes to their roles.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Cookies on nationaltrust.org.uk This website uses cookies. Some are essential … body.v--modal-block-scroll > div.cookie-preferences-forms > div.v--modal-overlay

ARIA dialog elements without accessible names may prevent screen readers users from discerning the purpose of these elements. Learn how to make ARIA dialog elements more accessible.

Why this matters

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

Source: MDN Permissions-Policy

Failing Elements
Cookies on nationaltrust.org.uk This website uses cookies. Some are essential … div.v--modal-overlay > div.v--modal-background-click > div.v--modal-box > div#cookieOptions

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.

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-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.
`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
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
Skip links are focusable.
Document has a main landmark.
Deprecated ARIA roles were not used
Uses ARIA roles only on compatible elements
Elements with visible text labels have matching accessible names.
`[accesskey]` values are unique
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.
`[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.
Image elements do not have `[alt]` attributes that are redundant text.
Identical links have the same purpose.
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.
100

Best Practices

General

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.

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
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`

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