In the Rigor Platform, we offer over 40 metrics to help you better understand your web performance. Along with these metrics we offer two scores: the Best Practices Score and The Performance Score, which directly is the Google Lighthouse Performance Score. This article will focus on the Performance Score and the way that Rigor calculates it.
The Performance Score, like Google Lighthouse, is a weighted average score that takes in 5 metrics: Time to Interactive, Speed Index, First Contentful Paint, First CPU Idle, and First Meaningful Paint and outputs a score from 0-100 that helps you understand your overall performance. It can be difficult to understand how to measure performance given so many metrics; the Performance score is intended to help in this area by combining the three important areas of web performance: speed, paint, and interactivity.
Why is my Rigor Performance Score different than Lighthouse?
There is really no difference between the makeup of Rigor's Performance Score and the Google Lighthouse Performance Score. The same math is used for both scores. However, you may see a difference in the output of the score. Where Lighthouse is limited to only running on your local machine with limited network configurations, The Rigor Performance Score has the ability to run with network throttling, different locations, different browsers and an array of viewport sizes. The difference in these inputs is what will change the output. As these inputs remain the same so will the score.
Why is there a "No Data" value given for the Performance Score?
This can be broken into three different situations:
1) One or more components may be missing.
Since the performance score is a composite score made of interdependent metrics it is possible that there will be no value shown for your performance score. This may be due to not having a timing for one of the 5 metrics listed above. For example:
By running a scan in Optimization of example.com we see that the Performance Score shows a "No data" value.
If we dig a little deeper into the Page Load Details we see that there is no timing for Speed Index. Since Speed Index is a required metric for calculating the Performance Score there will be a "no data" value given for that score. In Monitoring this will hold true for any of the other metrics related to the Performance Score as well.
2) The Optimization Scan/RBC Check is old and is not updated to reflect our new metrics.
It is important to keep in mind that since the Performance Score is a brand new score that takes in new metrics like: Time to Interactive and First CPU Idle, old scans/RBC checks which don't have these metrics will yield a "No data" value for the scan.
We can see this holds true for the monitoring dashboard. With these older RBC’s, it is possible that they do not contain the necessary components in order to calculate the Performance Score.
3) By uploading a HAR file straight to Optimization.
If you upload a HAR file to the Optimization scan you will also see a "No data" value given for the performance score, because all the components are not there in the HAR.