When running Lighthouse audit of website on chrome dev tools, turning on 'legacy navigation' really messes up website performance scores. It brings performance score down by 10-15 points on some URLs of my website and starts wildly fluctuating performance scores on other different URLs in my domain.

Can anyone explain to me what is legacy navigation and what does this setting exactly do in lighthouse in chrome dev tools? How's it related to the performance score?

Also, what are the actual settings that I should set on Google lighthouse to accurately represent how Google sees my mobile site in terms of SEO?

  • legacy navigation: Check or uncheck?
  • network settings: slow 3g or 4g? or no throttling for mobile?
  • cache settings: disable cache or no?
  • simulated throttling: Check or uncheck?
  • clear storage: Check or uncheck?

note: I run lighthouse on localhost as well so can't rely on pagespeed insights/webdev to see improvements from local changes.

1 Answer 1


In addition to what @tangible said, legacy mode enabled, the lighthouse analysis your site with the previus versions of lighthouse which is not generally recommended unless you want to test your site for older browsers.

Other options would be recommended as follow:

legacy navigation: uncheck (default) cache settings: disable cache simulated throttling: Default clear storage: Check

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