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Perceptual Speed Index - Printable Version

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Perceptual Speed Index - chelvan - 05-12-2017 03:54 AM

I understand there is a new perf metric that's available in Lighthouse called Perceptual Speed Index. (see info here https://github.com/pmdartus/speedline/) This is available from Chrome Dev Tools timeline. Wondering if this would be available in WPT?

RE: Perceptual Speed Index - pmeenan - 05-16-2017 11:07 PM

Not currently. It's a variant of the Speed Index code that uses SSIM instead of histograms for checking completeness.

The main difference is that it is sensitive to page elements moving (i.e. the page shifting down a few pixels would radically change the completeness %). That could be a good or a bad thing depending on how you felt about layout moving.