The Page Experience Update was a Google algorithm update for search that rolled out in Summer 2021. This update scores how well pages are optimised for users in terms of loading speed, usability, security, and ad experience.
- LCP (Largest Contentful Paint) – this is how long it takes for the largest item visible above the fold to load
- FID (First Input Delay) – this is how long it takes before a user can interact with content
- CLS (Cumulative Layout Shift) – this is how much the page moves after loading
Google measures each of these metrics by placing them into buckets of Good, Needs Improvement, and Poor, depending on your score.
These metrics can be measured in a number of ways, including through the free PageSpeed Insights tool.
As well as formalising Core Web Vitals being considered for search, Page Experience also covers pre-existing ranking signals such as mobile usability and security (the use of https).
Lab Data vs Field Data
It should be noted these metrics are measured using “Field Data” as opposed to “Lab Data”.
What this means is that instead of page speed being measured by a central computer, real-world results are collected (via people using Google Chrome) and that data is averaged out over a 28 day period.
This is a more accurate way of measuring page speed results as a specialized page speed testing computer will not encompass all the nuances found in the huge variety of machines, programs and operating systems found in the real world.
While this is a more accurate measure, the fact that results are averaged out over 4 weeks means that there will be a lag between updates to the site and measured results.