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.

Pass or fail?


CWV Breakdown

Largest Contentful Paint11.8 s3.6 s< 2.5 s
First Input Delay320 ms60 ms< 100ms
Cumulative Layout Shift0.0020.007 0.1

Tracking scripts

All the tracking scripts on the site generated ~678 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.

View details 2 203 KB 1 2 KB 2 9 KB 2 2 KB 3 15 KB 2 4 KB 1 6 KB 3 227 KB 2 4 KB 2 33 KB 1 7 KB 5 137 KB 1 620 B 1 837 B 2 220 B 1 443 B 1 0 B 1 0 B 1 467 B 3 3 KB 3 2 KB 4 1 KB 1 4 KB 1 3 KB 1 631 B 1 596 B 7 3 KB 3 3 KB 1 779 B 1 945 B 3 2 KB 2 2 KB


Remove autoplaying or preloaded media files1 video0.0 B

By removing 1 autoplaying or preloaded videos, roughly 0.0 B could be removed from the page load.

This would reduce the page transfer size by 0% and reduce the pages emissions from 1.02 grams of CO2 to 1.02 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.

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211215_UTAS_Banner_Final.mp4 0 B 0%
Optimise images990 KB0.255g

By optimising the following images, roughly 990 KB could be removed from the transfer size, about 25%. This would reduce the CO2 generated per page load from 1.02g grams to 0.76 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.
View details
young-people-with-science-blocks-hobart-open-day.jpg 266 KB 7% 82 KB
students-in-hobart-city.jpg 161 KB 4% 25 KB
event-400px.png 139 KB 4% 126 KB
event-400px.png 136 KB 3% 124 KB
sustainability-game-SDG-13-climate-action.jpg 119 KB 3% 39 KB
event-400px.png 113 KB 3% 103 KB
Naarah-Barnes.jpg 107 KB 3% 48 KB
Bob-Muller.jpg 95 KB 2% 40 KB
Amy-Walsh.jpg 89 KB 2% 41 KB
Dr-Yuan-Zhou.jpg 82 KB 2% 36 KB
Kruti-Patel.jpg 80 KB 2% 33 KB
211215_UTAS_Banner_Poster.jpg 79 KB 2% 14 KB
small.jpg 77 KB 2% 23 KB
tabs-wide-web.jpg 76 KB 2% 8 KB
small.jpg 67 KB 2% 22 KB
Clint-Steindl.jpg 64 KB 2% 31 KB
Dr-Chloe-Lucas.jpg 62 KB 2% 30 KB
Samantha-Sawyer.jpg 48 KB 1% 24 KB
environment-conservation-students-mt-paris-dam-derby-1.jpg 45 KB 1% 18 KB
Sarah-Chick.jpg 44 KB 1% 23 KB
Robbie-Arnott.jpg 42 KB 1% 21 KB
education-and-teaching-placement-taroona-primary-bush-class-1.jpg 40 KB 1% 17 KB
small.jpg 33 KB 1% 13 KB
law-students-hobart-city-law-precinct-1.jpg 23 KB 1% 10 KB
nursing-students-rozelle-campus-sydney-1.jpg 23 KB 1% 11 KB
fine-arts-design-student-hunter-street-campus-1.jpg 19 KB 0% 9 KB
flag1.png 17 KB 0% 16 KB
Subset large font files11 KB0.003g

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.

View details
montserrat-v15-latin-700.woff2 ~20 KB ~2 KB
montserrat-v15-latin-800.woff2 ~20 KB ~2 KB
montserrat-v15-latin-500.woff2 ~19 KB ~2 KB
montserrat-v15-latin-600.woff2 ~19 KB ~2 KB
montserrat-v15-latin-regular.woff2 ~19 KB ~2 KB
montserrat-v15-latin-300.woff2 ~19 KB ~2 KB
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.
Timing3.3 s1.9 s
Largest Contentful Paint

Largest Contentful Paint marks the time at which the largest text or image is painted. Learn more about the Largest Contentful Paint metric

Timing11.8 s3.6 s
Total Blocking Time

Sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds. Learn more about the Total Blocking Time metric.

Timing1,050 ms10 ms
Speed Index

Speed Index shows how quickly the contents of a page are visibly populated. Learn more about the Speed Index metric.

Timing9.5 s3.5 s
Time to Interactive

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.

Timing14.0 s3.1 s
Max Potential First Input Delay

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.

Timing320 ms60 ms
First Meaningful Paint

First Meaningful Paint measures when the primary content of a page is visible. Learn more about the First Meaningful Paint metric.

Timing3.3 s1.9 s
Eliminate render-blocking resources

Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles. Learn how to eliminate render-blocking resources.

InsightPotential savings of 800 msPotential savings of 480 ms
Reduce unused JavaScript

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

InsightPotential savings of 451 KiBPotential savings of 451 KiB
Serve images in next-gen formats

Image formats like WebP and AVIF often provide better compression than PNG or JPEG, which means faster downloads and less data consumption. Learn more about modern image formats.

InsightPotential savings of 990 KiBPotential savings of 990 KiB
Reduce initial server response time

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.

InsightRoot document took 220 msRoot document took 830 ms
Avoid enormous network payloads

Large network payloads cost users real money and are highly correlated with long load times. Learn how to reduce payload sizes.

InsightTotal size was 7,321 KiBTotal size was 3,944 KiB
Serve static assets with an efficient cache policy

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

Insight80 resources found79 resources found
Avoid an excessive DOM size

A large DOM will increase memory usage, cause longer style calculations, and produce costly layout reflows. Learn how to avoid an excessive DOM size.

Insight1,313 elements1,313 elements
JavaScript execution time

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.

Timing2.8 s0.4 s
Minimizes main-thread work

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

Timing5.7 s1.1 s
Minimize third-party usage

Third-party code can significantly impact load performance. Limit the number of redundant third-party providers and try to load third-party code after your page has primarily finished loading. Learn how to minimize third-party impact.

InsightThird-party code blocked the main thread for 900 msThird-party code blocked the main thread for 10 ms
Image elements do not have explicit width and height

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