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Understanding the Siteimprove Performance score?

Viktor Petersson avatar


This article discusses scores given within the Siteimprove performance module including:

How are the Performance scores calculated? 

Siteimprove Performance uses a Performance Score to represent the overall performance of a specific page, given the variables selected for the measurement.

Some pages could be scoring very high on certain devices, network speeds and from certain locations, while simultaneously providing a much slower experience given another set of variables.

The Performance scores allow users to easily cross-compare pages performance between these situations at a glance, and thus easily identify where you should direct your efforts.

The Performance score is based on the scoring scale used for Google’s Lighthouse. This scale weighs different metrics using a range of multipliers, as Google considers some metrics more impactful than others when determining the overall speed and experience offered to users. This allows us to better understand interactivity, as older technologies and tests would simply measure the time-to-load for different assets, without adjusting for the degree of interactivity offered to the end-user.

The table below shows the weighting used for different metrics on Google’s scale. For more information on the metrics used in the table see the article - Performance: Terminology.

Metric Weighting
First Contentful Paint 15%
Largest Contentful Paint 25%
Total Blocking Time 25%
Time to Interactive 15%
Speed Index 15%
Cumulative Layout Shift 5%

For example, this means that when weighing the impact of these metrics, First Contentful Paint is weighed 15%, whereas Total Blocking Time is weighed 25%.  This means Total Blocking Time weighs heavier when calculating the score than First Contentful Paint. 

What can be considered a good Performance score?

Performance will return a score between 0-100 for each monitoring, given the specific metrics selected.  A score of 0 is valid and usually indicates a very slow and poor experience, whereas a score of 100 indicates an excellent and very fast experience.

The following ranges give an indication of how your site is doing:

  • Red: 0-49 (poor)
  • Orange: 50-89 (average)
  • Green: 90-100 (good)

A score of 90+ will place you in the top 5% of websites, according to Google’s own scale for determining a page’s performance and speed. Reaching this score will improve your SEO, user engagement and user experience which can all help to increase conversion rates.

To improve the scores for a site being monitored you can utilize the techniques provided in the Performance Suggested Improvements section in the platform. 

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