Blue Mountains City Council

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 Paint10.9 s2.6 s< 2.5 s
First Input Delay1,750 ms460 ms< 100ms
Cumulative Layout Shift00.011 0.1


Optimise images

By optimising the following images, roughly 3 MB could be removed from the transfer size, about 49%. This would reduce the CO2 generated per page load from 1.52g grams to 0.78 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.
EcoDestinationLaunch_HS.jpg 2 MB 27% 1 MB
EcoDestinationLaunch_TH.jpg 1 MB 25% 1 MB
GangGangCockatoo-JohnFrench_TH.jpg 384 KB 7% 140 KB
Apprentice2023_CallamCorney_with_MurrayWakely.jpg 293 KB 5% 49 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.

Frutiger-LT-Std-65-Bold.ttf ~21 KB ~4 KB
Frutiger-LT-Std-55-Roman.ttf ~21 KB ~3 KB
Frutiger-LT-Std-45-Light.ttf ~21 KB ~3 KB
glyphicons-halflings-regular.woff2 ~18 KB ~551 B

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.
Timing1.4 s0.4 s

Largest Contentful Paint

Timing10.9 s2.6 s

Total Blocking Time

Timing1,490 ms1,010 ms

Speed Index

Timing10.4 s3.3 s

Time to Interactive

Timing17.1 s4.2 s

Max Potential First Input Delay

Timing1,750 ms460 ms

First Meaningful Paint

Timing3.3 s0.7 s

Eliminate render-blocking resources

InsightPotential savings of 230 ms

Minify JavaScript

InsightPotential savings of 23 KiBPotential savings of 23 KiB

Reduce unused CSS

InsightPotential savings of 32 KiBPotential savings of 25 KiB

Reduce unused JavaScript

InsightPotential savings of 646 KiBPotential savings of 642 KiB

Efficiently encode images

InsightPotential savings of 250 KiBPotential savings of 250 KiB

Serve images in next-gen formats

InsightPotential savings of 1,711 KiBPotential savings of 1,941 KiB

Avoid enormous network payloads

InsightTotal size was 5,362 KiBTotal size was 5,902 KiB

Serve static assets with an efficient cache policy

Insight37 resources found38 resources found

Avoid an excessive DOM size

Insight1,213 elements1,213 elements

Reduce JavaScript execution time

Timing5.8 s2.7 s

Minimize main-thread work

Timing8.2 s4.1 s

Ensure text remains visible during webfont load


Reduce the impact of third-party code

InsightThird-party code blocked the main thread for 3,550 msThird-party code blocked the main thread for 1,720 ms

Uses passive listeners to improve scrolling performance


Image elements do not have explicit width and height