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Performance module upgrade - December 29, 2021
Performance module upgrade - December 29, 2021

The Performance module has been updated to run on the new version of Google Lighthouse and you'll likely see a change in your scores

Updated over a week ago

The upgrade consists of two changes:

1. Upgrade to new version of Google Lighthouse

Monsido has upgraded to a new performance weight system with Google Lighthouse version 8.5. Google Lighthouse is the tool that delivers data to the Performance module. In version 8.5, new metrics are added while others are removed. At the same time, the weighting of the different metrics in the calculation of the overall score is changing. For those reasons, you are likely to see a change in your Performance Score as a result of the upgrade.

The following metrics are removed:

  • First Meaningful Paint

  • First CPU Idle

The following metrics are added:

  • Largest Contentful Paint: This metric represents the time duration between the user initiating the page load and the page rendering its primary content.

  • Total Blocking Time: This is the sum of all time periods between First Contentful Paint and Time to Interactive, expressed in milliseconds.

  • Cumulative Layout Shift: This is the measurement of the movement of visible elements within the viewport.

Some of these scores are not visible in the report but are calculated into the score in the background.

The History Center displays an indication that the version has changed, to help users understand why the Performance score shows a sudden jump.

For more information on how the scores are calculated after the upgrade, see:

2. Excluding archived profiles from the Average Performance score

In the History Center, we display an Average Performance score which is calculated as the average of all the Performance Scores of your pages. For example, if you are running performance scans on six pages, the Average Performance score is the average score of those six.

Before, this score also factored in profiles on performance pages that are archived. Monsido has changed this so that archived profiles are disregarded from the Average Performance score calculation. This makes the score more accurate. This only affects your score if you have archived Performance profiles on your Monsido account.

Additional information from Google Lighthouse on the Lighthouse 8.5 upgrade

How the Performance score is weighted:

The Performance score is a weighted average of the metric scores. Naturally, more heavily weighted metrics have a greater effect on your overall performance score.

The metric scores are not visible in the report but are calculated in the background.

The weightings are chosen to provide a balanced representation of the user's perception of performance.

Lighthouse scoring calculator webapp

Explore scoring with the Lighthouse scoring calculator

Lighthouse 8 #

How metric scores are determined #

When the performance metrics are gathered, (mostly reported in milliseconds), Lighthouse converts each raw metric value into a metric score from 0 to 100 by looking where the metric value falls on its Lighthouse scoring distribution.

Additional Information

The IP addresses used for the Performance Module are:


See the following articles for more information:

For further assistance, contact the Monsido support team or via the Monsido chat and help features inside the application.

Image of the Dashboard with the location of the Help Center buttons highlighted.

See Monsido for Developers for documentation containing information that developers need to know.


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