James Cook University Australia

The Index


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 Paint15.3 s2.5 s< 2.5 s
First Input Delay370 ms180 ms< 100ms
Cumulative Layout Shift0.0010.049 0.1

Tracking scripts

All the tracking scripts on the site generated ~788 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.

google-analytics.com 6 24 KB
googletagmanager.com 2 186 KB
stats.g.doubleclick.net 4 2 KB
google.com 7 5 KB
googleads.g.doubleclick.net 4 8 KB
googleadservices.com 1 2 KB
connect.facebook.net 5 379 KB
snap.licdn.com 1 5 KB
redditstatic.com 1 8 KB
siteimproveanalytics.com 1 11 KB
api.ipify.org 1 157 B
js.adsrvr.org 2 3 KB
sc-static.net 2 27 KB
analytics.tiktok.com 5 101 KB
img.en25.com 1 3 KB
alb.reddit.com 1 603 B
tr.snapchat.com 5 3 KB
analytics.google.com 2 0 B
cdn.linkedin.oribi.io 2 940 B
px.ads.linkedin.com 3 3 KB
google.com.au 1 620 B
facebook.com 12 2 KB
pixel.tapad.com 2 2 KB
gtm-nmmh8cl-ndy2n.uc.r.appspot.com 2 2 KB
linkedin.com 1 2 KB
insight.adsrvr.org 1 580 B
match.adsrvr.org 4 4 KB
pixel.rubiconproject.com 1 945 B
ups.analytics.yahoo.com 2 1 KB
cm.g.doubleclick.net 1 764 B


Remove autoplaying or preloaded media files

By removing 2 autoplaying or preloaded videos, roughly 18.7 MB could be removed from the page load.

This would reduce the page transfer size by 86% and reduce the pages emissions from 5.76 grams of CO2 to 0.82 grams of CO2.

Autoplaying videos can have a negative impact on the user experience for several reasons:

  1. Increased data usage: Autoplaying videos can consume a lot of data, especially if they are set to play in high definition. This can be a problem for users with limited data plans or slow connections, who may experience slow or interrupted playback.
  2. Annoyance factor: Autoplaying videos can be annoying for users, especially if they are accompanied by sound. This can lead to a negative perception of the website and decreased engagement.
  3. Reduced accessibility: Autoplaying videos can be a problem for users with accessibility needs, such as users who are blind or have hearing difficulties.
  4. Increased page load time: Autoplaying videos can increase the overall page load time, leading to a slower user experience.
  5. Decreased battery life: Autoplaying videos can consume a lot of battery power, especially on mobile devices, leading to reduced battery life.

In order to minimise the impact of autoplaying videos on the user experience, it is recommended to use them sparingly and only when necessary. It is also important to provide users with the option to turn off autoplaying videos and to allow them to control the playback of videos on the page. Additionally, videos should be optimised for performance and should be accompanied by captions or transcripts to improve accessibility.

JCUWorldAnimation_Proof5%20%281%29.mp4 15 MB 68%
JCUWorldAnimation.webm 4 MB 18%

Optimise images

By optimising the following images, roughly 1 MB could be removed from the transfer size, about 5%. This would reduce the CO2 generated per page load from 5.76g grams to 5.46 grams.

Images should be optimised for the web for several reasons:

  1. Reduced file size: Optimizing images can result in a smaller file size, which can help to reduce the amount of data that needs to be downloaded. This can lead to faster page load times and improved performance.
  2. Improved user experience: Optimising images can help to improve the overall user experience, as pages with optimised images load faster and are more responsive.
  3. Lower emissions: Optimising images can help to reduce the emissions associated with data transfer, as less data needs to be transmitted over the network.
  4. Better accessibility: Optimising images can make them more accessible to users with slower connections or limited data plans.
fullhd.jpg 780 KB 3% 232 KB
fullhd.jpg 780 KB 3% 232 KB
fullhd.jpg 246 KB 1% 97 KB
fullhd.jpg 185 KB 1% 82 KB
fullhd.jpg 165 KB 1% 78 KB
Acc_CTA.jpg 152 KB 1% 50 KB
tiles.png 143 KB 1% 126 KB
tiles.png 120 KB 1% 108 KB
tiles.png 98 KB 0% 90 KB
two-thirds-tile.jpg 50 KB 0% 14 KB
tiles.png 48 KB 0% 40 KB
two-thirds-tile.jpg 36 KB 0% 15 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.

memvYaGs126MiZpBA-UvWbX2vVnXBbObj2OVTS-mu0SC55I.woff2 ~39 KB ~22 KB
nuFvD-vYSZviVYUb_rj3ij__anPXJzDwcbmjWBN2PKdFvXDXbtXK-F2qC0s.woff ~24 KB ~6 KB

Convert font files to woff2

WOFF2 is considered to be the best font format for web use because it provides a good balance of file size and compatibility. Some specific reasons why WOFF2 is a good font format include:

  1. Small file size: WOFF2 is a compressed font format, which means that it has a smaller file size compared to other font formats like TTF or OTF. This is important for web use because smaller file sizes can help to reduce the amount of data that needs to be downloaded, leading to faster page load times.
  2. High-quality font rendering: WOFF2 provides high-quality font rendering, making it a good choice for use on the web.

It’s worth noting that WOFF2 is not the only font format that can be used on the web, and there may be cases where other formats like WOFF or TTF are more suitable, depending on the specific requirements of the website. However, for most cases, WOFF2 is considered to be the best font format for web use due to its combination of small file size, good browser support, and high-quality font rendering.


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.

Replace jQuery and jQuery libraries with more modern code

jQuery is a popular and widely-used JavaScript library that simplifies web development by providing a set of tools and functions to interact with HTML documents, handle events, create animations, and make asynchronous HTTP requests.

In the past, jQuery was a very popular choice for web development because it simplified many common tasks and provided a consistent and cross-browser-compatible API. However, with the advancement of modern web technologies and improvements in browser capabilities, the need for jQuery has decreased.

Many modern web frameworks and libraries, such as React and Angular, provide their own set of tools for handling common tasks and interacting with the DOM, making jQuery less necessary in many cases. The Javascript engine in modern browsers have also become more consistent in the feature implementations often eliminating the need for a library like jQuery.

jQuery represents an opportunity because:

  1. Performance: While jQuery is a powerful and useful library, it can slow down website performance due to its large size and complex code. Modern browsers have also improved their native support for many of the features that jQuery provides, reducing the need for it.
  2. Maintainability: jQuery code can be difficult to maintain and update, particularly as web technologies evolve and change. This can make it harder for developers to keep up with best practices and standards for web development.
  3. Accessibility: Some jQuery plugins and features can create accessibility issues, particularly for users who rely on assistive technologies. This can make it harder for people with disabilities to use and access websites.

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.
Timing2.9 s0.8 s

Largest Contentful Paint

Timing15.3 s2.5 s

Total Blocking Time

Timing960 ms160 ms

Cumulative Layout Shift


Speed Index

Timing6.8 s2.5 s

Time to Interactive

Timing12.6 s2.6 s

Max Potential First Input Delay

Timing370 ms180 ms

First Meaningful Paint

Timing2.9 s0.8 s

Eliminate render-blocking resources

InsightPotential savings of 1,150 msPotential savings of 240 ms

Minify JavaScript

InsightPotential savings of 29 KiBPotential savings of 29 KiB

Reduce unused CSS

InsightPotential savings of 20 KiB

Reduce unused JavaScript

InsightPotential savings of 409 KiBPotential savings of 407 KiB

Serve images in next-gen formats

InsightPotential savings of 641 KiBPotential savings of 932 KiB

Reduce initial server response time

InsightRoot document took 900 msRoot document took 910 ms

Avoid serving legacy JavaScript to modern browsers

InsightPotential savings of 73 KiBPotential savings of 73 KiB

Avoid enormous network payloads

InsightTotal size was 2,953 KiBTotal size was 22,329 KiB

Serve static assets with an efficient cache policy

Insight44 resources found58 resources found

Avoid an excessive DOM size

Insight1,212 elements1,215 elements

JavaScript execution time

Timing2.6 s0.6 s

Minimizes main-thread work

Timing5.8 s1.6 s

Ensure text remains visible during webfont load


Minimize third-party usage

InsightThird-party code blocked the main thread for 790 msThird-party code blocked the main thread for 200 ms

Does not use passive listeners to improve scrolling performance