GTmetrix Performance Blog

News, updates and guides on GTmetrix and general web performance

Updated to Lighthouse 12.3, New CLS Audit Details, and Scoring Changes

We’ve upgraded GTmetrix to Lighthouse 12.3.0 – read on for important changes that come with this release.


 

New Lighthouse Version

Moving from Lighthouse 11.0.0 to 12.3.0 saw some relevant changes to CLS scoring methodology as well as various audits.

 


 

New Avoid large layout shift details and categories

Lighthouse 12.3.0 brings an update to the CLS related audit Avoid large layout shifts, detailing new root causes of detected layout shifts.
 

New root causes of CLS are now detailed in the Avoid large layout shifts audit.

 
Other root causes include:

  • Media element lacking an explicit size
  • Web font loaded
  • A late network request adjusted the page layout
  • Injected iframe

Read more about all the root CLS causes here in our Avoid large layout shifts documentation.
 


 

Scoring Methodology Changes

Changes in scoring methodologies were also introduced with Lighthouse 12.3.0, including how certain audit scores are calculated.

As a result, scores may have shifted slightly, but we are still primarily focusing on what audits are impacting your page/web vitals.

We will be monitoring data as this release rolls out and making modifications to weights and scoring as we deem necessary.
 


 

Other Changes

  • Chrome updated to v125.0.0
     
  • CSV Export Updates
    • When exporting multiple history CSVs, files will use full URL as filenames for better differentiation.
    • Same domain exports should now be more distinguishable.
       
  • CDN Updates
    • Added Verge Cloud CDN
       
  • Minor bug fixes and updates.

 


 
Let us know if you run across any bugs or issues and feel free to tell us your thoughts on Twitter (@gtmetrix) or contact us.


 

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