Lighthouse 2.6 Updates
Lighthouse 2.6 is out! Highlights include:
- New performance audits.
- A rehaul of the accessibility section score.
- Improvements to the report UX.
- A bug fix for the aspect ratio audit.
See the 2.6 release notes for the full list of new features, changes, and bug fixes.
How to update to 2.6
- NPM. Run
npm update lighthouse. Runnpm update lighthouse -gflag if you installed Lighthouse globally. - Chrome Extension. The extension should automatically update, but you can manually update it
via
chrome://extensions. - DevTools. The Audits panel will be shipping with 2.6 in Chrome 65. You can check what version
of Chrome you're running via
chrome://version. Chrome updates to a new version about every 6 weeks. You can run the latest Chrome code by downloading Chrome Canary.
New performance audits
JavaScript boot-up time is high
View a breakdown of the time your page spends parsing, compiling, and executing each script. JavaScript boot-up time is a somewhat-hidden but important factor in page load time.
Uses inefficient cache policy on static assets
Make sure that the browser properly caches each of your resources.
Avoids page redirects
Page redirects add an extra network roundtrip, or two if an extra DNS lookup is required. Minimize redirects in order to speed up page load time.
Rehaul of the accessibility section score
In Lighthouse 2.6, the aggregate accessibility score is calculated differently. The score weighs each accessibility audit based on the severity of its impact on user experience, as well as the frequency of the issue, based on the HTTP Archive dataset. See googlechrome/lighthouse/issues/3444 for an in-depth discussion.
Report UX Improvements
Note: These updates are in the Chrome Extension version of Lighthouse only. They are not yet in the Audits panel of DevTools.
Top-level errors
At the top of your report, Lighthouse alerts you to errors that may have affected your page's scores.
Print summary and expanded views
Click Export Report 
then select Print Summary or
Print Expanded to print out summarized or detailed versions of your reports.
Aspect ratio bug fix
2.6 also fixes a bug that caused the Displays images with correct aspect ratio audit to fail even when there were no images on the page, or all images were properly sized.