Fundamental Review: Update of Core Web Vitals white paper with new information about INP

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One of the key metrics of Core Web Vitals, which appeared in the spring of 2024, is Interaction to Next Paint (INP). This is a metric that measures how quickly a site responds to user actions, such as clicks, pressing buttons on the keyboard or screen. The difference between INP and other similar metrics, such as First Input Delay, is that INP measures the delay of all actions on a page, not just the first.

"INP monitors the latency of all user actions on the page and reports a single value that is less than or equal to all (or nearly all) actions. A low INP means that the page was able to respond quickly to all or the vast majority of user actions."

One of the key updates to the documentation is the explanation of performance thresholds that indicate whether a site is performing poorly, needs improvement, or is performing well. When determining these threshold values, the developers were guided by the following principles. 🚀

• 📌 The difference in the usage characteristics of mobile and desktop devices affects the "achievability" of the thresholds, but since the user's perception of a good or bad experience does not depend on the device, it was decided not to separate the thresholds by device type.
• 📌 Creating a single, mobile-based threshold makes thresholds easier to understand.
• 📌 Devices are not always clearly divided into categories. Therefore, it was decided that using the same threshold values ​​helps to avoid this complexity.

Regarding the thresholds for INP assessment, it was decided that less than 200 ms was considered a “good” result, 200 ms to 500 ms “needs improvement”, and more than 500 ms was considered a “poor” result. 🚀

It is important to note that when determining INP thresholds, the fact that many users visit sites from low-performance mobile devices was also taken into account. 🚀

"We also paid additional attention to the reach of INP traversal for lower mobile devices, where they accounted for a large proportion of site visits. This further confirmed the suitability of the 200ms threshold."

Another interesting detail that was taken into account when determining the INP thresholds is the performance of the most popular sites. The developers studied the performance of the top 10,000 websites because they account for a large portion of all site visits. 🚀