BOOST YOUR PAGESPEED INSIGHTS SCORE

Performance is a core foundation of great user experience. Google Chrome engineering manager Addy Osmani shows you how PageSpeed Insights gives you a to-do list for UX improvements to so you can get fast and stay fast

- Addy Osmani

Hey folks. My name is Addy Osmani and I manage the Web Developer Insights team in Chrome, where we work on tools like PageSpeed Insights (https:// bit.ly/pagespeed-insights) and Lighthouse (https://bit.ly/lighthouse-tool). Here, we’re going to talk about the best thing since sliced bread: performance measurement.

When you’re building a modern web experience, it’s important to measure, optimise and monitor if you’re to get fast and stay fast. Performance plays a significant role in the success of any site, as high-performing sites engage and retain users better than poorlyperforming ones. Tools like PageSpeed Insights (PSI) and Lighthouse can be valuable for monitoring the performance of your sites. But what do they do?

Lighthouse offers a comprehensive set of performance opportunities and the time saved by implementing each optimisation. You can find it in the Chrome DevTools Audits panel and in PageSpeed Insights.

PageSpeed Insights reports on the performance of a page on mobile and desktop devices and provides suggestions on how that page may be improved.

PSI provides both ‘lab’ (Lighthouse) and ‘field’ data about a page. Lab data is useful for debugging performance issues, as it is collected in a controlled environment. However, it may not capture real-world bottlenecks. Field data is useful for capturing true, real-world user experience but has a more limited set of metrics.

Performance score

At the top of the report, PSI provides a score that summarises the page’s performance. This score is determined by running Lighthouse to collect and analyse lab data about the page. A score of 90 or above is considered fast and 50 to 90 is considered moderate. Below 50 is considered to be slow.

Lab versus field data

Lab data