Google Lighthouse Performance

The Google Lighthouse performance score is a metric that measures the speed and performance of a website. It’s an overall score that ranges from 0 to 100 and is generated based on a number of different performance metrics, such as the time it takes for a website to load, the time it takes for a website to become interactive, the size of the resources used by the website, and other factors that impact the user experience.

A high performance score in Google Lighthouse indicates that a website is fast and responsive, which can lead to a better user experience and improved search engine rankings. On the other hand, a low performance score can indicate that a website is slow and unresponsive, and can negatively impact the user experience.

Mobile Performance
Desktop Performance

Core Web Vitals

Core Web Vitals are a set of specific factors that Google considers important in a webpage’s overall user experience. Core Web Vitals are made up of three specific page speed and user interaction measurements: Largest Contentful PaintFirst Input Delay, and Cumulative Layout Shift.

Largest Contentful Paint20.8 s3.7 s< 2.5 s
First Input Delay1,520 ms320 ms< 100ms
Cumulative Layout Shift0.1260.199 0.1

Tracking scripts

All the tracking scripts on the site generated ~599 KB of data

A tracking script is a code snippet designed to track the flow of visitors who visit a website. Media, advertising, and analytics organisations will provide a script to add to your website that sends data directly to their servers. This data can then be used to measure goals and conversions, analyse user behaviour, and influence advertising campaigns.

Consider how much of this data you actually need and use? How often do you review the analytics data, and does this inform genuine change? Are you actively running social media campaigns? Consider pausing or removing tracking scripts that aren’t being actively used. 3 58 KB 1 7 KB 2 1 KB 1 9 KB 2 419 B 3 2 KB 13 10 KB 3 3 KB 2 1 KB 8 184 KB 4 74 KB 1 126 B 16 12 KB 3 3 KB 2 940 B 2 720 B 2 1 KB 9 5 KB 1 603 B 1 577 B 1 768 B 1 197 B 1 2 KB 16 12 KB 2 774 B 1 642 B 2 526 B 2 1 KB 1 660 B 3 953 B 1 577 B 5 3 KB 1 0 B 6 2 KB 5 95 KB 3 2 KB 3 10 KB 6 4 KB 1 738 B 1 734 B 1 432 B 3 2 KB 1 435 B 1 398 B 1 962 B 3 2 KB 2 2 KB 9 8 KB 3 2 KB 1 606 B 5 3 KB 2 2 KB 17 10 KB 1 836 B 1 413 B 6 8 KB 1 673 B 1 1 KB 2 2 KB 1 17 KB 4 4 KB 1 855 B 5 4 KB 1 702 B 10 6 KB 2 712 B 2 1 KB 1 698 B 1 559 B 2 1 KB 2 939 B 1 735 B 2 2 KB


Subset large font files

Fonts should be subsetted to reduce the file size, improve performance, and reduce emissions. Subsetting a font involves removing any characters that are not needed for a particular use case, resulting in a smaller file size and faster page load times. Some specific reasons why fonts should be subsetted include:

  1. Reduced file size: Subsetting a font removes any unused characters, which can result in a smaller file size. This can help to reduce the amount of data that needs to be downloaded, leading to faster page load times and lower emissions.
  2. Improved performance: Fonts that are subsetted are faster to load and render than fonts that are not subsetted. This can help to improve the overall performance of a website, leading to a better user experience.

Overall, subsetting fonts is a good practice for anyone looking to optimize the performance and reduce the emissions of a website of a website.

cnnsans-italic.woff2 ~48 KB ~30 KB
cnnsans-lightit.woff2 ~48 KB ~30 KB
cnnsans-regular.woff2 ~47 KB ~29 KB
cnnsans-light.woff2 ~46 KB ~29 KB
cnnsans-bold.woff2 ~36 KB ~18 KB
cnnsans-medium.woff2 ~35 KB ~17 KB
cnn-icons.woff2 ~22 KB ~4 KB

Remove third party font files

Font files should be loaded from the same hosting as the website because

  1. Increased loading time: Third-party sub-resources, such as scripts, fonts, or images, need to be downloaded from a separate server before they can be displayed on the website. This can increase the overall loading time of the page, leading to a slower user experience.
  2. Dependence on external servers: The loading of third-party subresources is dependent on the availability and performance of the external servers that host them. If these servers are slow or unavailable, it can result in slow page loading times or even errors.
  3. Increased risk of security threats: Third-party subresources can introduce security risks to a website, as they can contain malicious code or be used to track user activity.

First Contentful Paint

First Contentful Paint (FCP) is a performance metric that measures the time it takes for the first piece of content to be rendered on the screen when a user navigates to a web page. This content can be any visual element on the page, such as text, images, or a background color.

FCP is important because it directly affects the perceived speed of a website, and can impact user engagement and conversion rates. A faster FCP can lead to a better user experience and improved performance.

Here are a few ways you can optimise your FCP:

  1. Optimise images: Large, unoptimised images can slow down a page’s FCP. You can optimise images by compressing them, reducing their dimensions, and choosing the right format for each image.
  2. Minimise HTTP requests: Each resource requested by a web page, such as images, scripts, and stylesheets, requires a separate HTTP request. Minimising the number of HTTP requests can help to reduce the time it takes for a page to render.
  3. Prioritize critical content: Prioritizing critical content, such as above-the-fold content, can help to ensure that users see something on the screen quickly, even if the rest of the page is still loading.
  4. Reduce server response time: A slow server response time can significantly impact FCP. Optimizing server-side code and server settings can help to reduce response times and improve FCP.
  5. Use a performance monitoring tool: There are many tools available that can help you monitor your website’s performance, including FCP. These tools can help you identify performance issues and track your progress as you implement optimizations.
Timing9.5 s1.8 s

Largest Contentful Paint

Timing20.8 s3.7 s

Total Blocking Time

Timing8,870 ms1,350 ms

Cumulative Layout Shift


Speed Index

Timing19.2 s4.0 s

Time to Interactive

Timing48.1 s8.2 s

Max Potential First Input Delay

Timing1,520 ms320 ms

First Meaningful Paint

Timing10.3 s2.3 s

Defer offscreen images

InsightPotential savings of 100 KiBPotential savings of 100 KiB

Reduce unused CSS

InsightPotential savings of 136 KiBPotential savings of 114 KiB

Reduce unused JavaScript

InsightPotential savings of 2,164 KiBPotential savings of 1,194 KiB

Efficiently encode images

InsightPotential savings of 40 KiB

Serve images in next-gen formats

InsightPotential savings of 78 KiBPotential savings of 135 KiB

Enable text compression

InsightPotential savings of 15 KiBPotential savings of 15 KiB

Remove duplicate modules in JavaScript bundles

InsightPotential savings of 4 KiBPotential savings of 4 KiB

Avoid serving legacy JavaScript to modern browsers

InsightPotential savings of 97 KiBPotential savings of 68 KiB

Preload Largest Contentful Paint image

InsightPotential savings of 1,350 msPotential savings of 200 ms

Avoid enormous network payloads

InsightTotal size was 5,969 KiBTotal size was 4,278 KiB

Serve static assets with an efficient cache policy

Insight105 resources found107 resources found

Avoid an excessive DOM size

Insight1,316 elements1,503 elements

Reduce JavaScript execution time

Timing19.4 s4.7 s

Minimize main-thread work

Timing28.3 s8.0 s

Ensure text remains visible during webfont load


Reduce the impact of third-party code

InsightThird-party code blocked the main thread for 6,240 msThird-party code blocked the main thread for 390 ms

Uses passive listeners to improve scrolling performance


Avoid document.write()


Image elements do not have explicit width and height