We’ve upgraded GTmetrix to Lighthouse 8.3.0 – read on for changes that come with this release.

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Lighthouse 8.3.0

Moving from Lighthouse 7.4.0 to 8.3.0 saw a few notable changes, primarily the re-weighting of Performance scores.
 

Performance Score Re-weighted

The Performance score is compromised of 6 individual metrics that were weighted and combined to produce a single score.

With our update to Lighthouse 8.3.0, these individual metrics have been adjusted with a new weighting:
 

First Contentful Paint (FCP) Previously 15%, now at 10% (▼ 5%)   Speed Index (SI) Previously 15%, now at 10% (▼ 5%)   Time to Interactive (TTI) Previously 15%, now at 10% (▼ 5%)

Total Blocking Time (TBT) Previously 25%, now at 30% (▲ 5%)   Cumulative Layout Shift (CLS) Previously 5%, now at 15% (▲ 10%)   Largest Contentful Paint (LCP) No Change – Remains at 25%

 
This new weighting places more importance on reduced JavaScript execution and a more visually stable page load.

For more specifics on the weighting change, read Lighthouse’s official FAQ.
 

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Other Relevant Changes from Lighthouse 7.4.0 to 8.3.0

• Properly size images audit will now ignore images larger than the viewport
   
• “Serve images in next-gen formats” audit key (serve-images-in-next-gen-formats) is renamed to “modern-image-formats”
  • Applicable to API users only
     
• Serve images in next-gen formats now includes AVIF estimates
  • Read more information on the AVIF image format here
     
• Temporarily disable all preload audits
  • Including “Preload key requests” and “Preload Largest Contentful Paint image”
  • Preloading is still a good strategy to practice, however aggressive preloading can cause performance issues (i.e. preloading everything)
  • Further discussion/research is needed on how to better present preloading recommendations in the audits (Source)
     
• Fixed resource size calculation of cached images

 

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More GTmetrix Fixes

We’ve also tweaked and fixed a few other Lighthouse related issues:

• Fixes to Speed Visualization (Filmstrip)
  • Corrected situation where the Speed Visualization extended past the Fully Loaded time in some conditions
     
• Fixes to Lighthouse and Redirected Pages
  • Fixed Lighthouse abort errors with certain odd redirects
  • Fixed missing items in critical request changes with certain redirect conditions

 

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General updates and improvements

More changes in this release:
 

Analysis Option Flags on Dashboard Now Show Regions Within Countries

To help differentiate locations within the same country, we’ve added abbreviations to flag icons.
 

 
You can now see at a glance which specific location within a country you’ve tested in.

 

Other Updates

• PDF Report Fixes
  • Fixed PDF styling bug where content overlapped the header in Full Reports in some cases
     
• API Documentation Updates
  • View the API v2.0 changelog here

 

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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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