Our Test Agents are now using Lighthouse 10.2.0 to test your Sites.
The upgrade from Lighthouse 9.x to 10.x introduces several changes to the way Lighthouse calculates performance metrics. You can find details on the official Lighthouse 10 changelog.
Key changes:
- Time to Interactive (TTI) is no longer used to calculate Performance Score.
- Cumulative Layout Shift (CLS) is responsible for 25% of the Performance Score (up from 15%).
- Lighthouse now calculates Time to First Byte (TTFB). Calibre is now using the Lighthouse TTFB calculation, instead of its previous measurements.
- Lighthouse calculates Largest Contentful Paint (LCP) phases, which are surfaced in the Largest Contentful Paint Element audit.
- New Back/Forward Cache audit.
- Lighthouse dropped the inclusion of Chrome-Lighthouse in the User-Agent header; however, Calibre will continue to include this header.
- Previously unknown Third Parties are now identified by the Third Party report. You may notice an increase in Total Third Party Code Transferred or Total Third Party Main Thread Execution Time metrics as a result of newly identified third parties.
As a consequence of first two points, your Performance Score might change.