Introduction to Lighthouse 13
Google has released Lighthouse 13, an update that brings significant changes to the auditing process. This update aims to align Lighthouse reports with Chrome DevTools’ newer insight model, making it easier for developers to identify and fix issues. The update is available now via npm and Chrome Canary, and it will roll into PageSpeed Insights within about a week and is slated for Chrome’s stable channel with version 143.
What’s New in Lighthouse 13
The update doesn’t change how Lighthouse calculates performance scores, but it does target non-scored audits. Lighthouse 13 replaces many legacy audits with "insights" that mirror DevTools, providing a more streamlined and efficient way to identify and fix issues.
Audit Consolidation
Notable examples of the new insights include:
- CLS And Layout: layout-shifts becomes cls-culprits-insight for clearer identification of layout shift causes.
- Server And Network: document-latency-insight consolidates redirects, server response time, and text compression checks.
- Images: image-delivery-insight replaces modern formats, optimized images, responsive images, and efficient animated content audits.
- LCP: Two insights break down Largest Contentful Paint issues: lcp-discovery-insight and lcp-phases-insight. For interaction work, see interaction-to-next-paint-insight (INP).
- Third-Party: third-parties-insight replaces the older third-party summary to show external script impact.
Additional replacements address DOM size, duplicated JavaScript, font display, legacy JavaScript, HTTP/2 and modern HTTPS, network dependency trees, render-blocking, caching, and viewport configuration.
Removed Audits
Several audits were removed because they are outdated, inactionable, or low value in modern environments. Removed audits include:
- first-meaningful-paint
- font-size
- offscreen-images
- preload-fonts
- uses-rel-preload
- no-document-write
- uses-passive-event-listeners
- third-party-facades
Minor Differences From Earlier Previews
Google kept non-composited-animations and unsized-images as separate diagnostics to help locate issues that don’t directly cause CLS. Google also removed font-size and preload-fonts even though those were not in the initial removal list.
Why This Matters
If you rely on Lighthouse for client reporting, you will see fewer line items and more consolidated insights that map to DevTools. Your scores shouldn’t change just by upgrading, but any automation that keys off audit IDs will need to track the new insight identifiers. For SEO context, the removal of the font-size audit reflects Google’s position that this is not a current SEO signal, even though legibility remains a UX consideration.
Looking Ahead
Expect Lighthouse and DevTools to stay aligned on the same insight model. For reporting, consider mapping old audit IDs to the new insights now to avoid broken dashboards when PSI updates.
Conclusion
Lighthouse 13 is a significant update that brings many changes to the auditing process. By understanding these changes, developers can better identify and fix issues, improving the overall performance and user experience of their websites. With the update available now, it’s essential to start exploring the new insights and adjustments to ensure a smooth transition and take advantage of the improved auditing capabilities.