WebVitals INP Score: Monitoring and Improving User Experience with Pubperf
Transfon Team
4 min read
Web performance is key to providing a positive user experience on the web. To ensure that websites are responsive and interactive, web developers and publishers need to monitor and optimize various performance metrics. One such important metric is the Interaction to Next Paint (INP) score, which has recently gained support and is now integrated into Pubperf analytics.
INP is a Core Web Vital metric that replaced First Input Delay (FID) as a Core Web Vital in March 2024. It focuses on assessing a page's responsiveness by measuring the latency of all user interactions throughout a user's visit to a website. The INP score provides worthwhile insights into how well a page can respond quickly to user actions.
Traditionally, metrics like FID only considered the first interaction on a page. However, INP takes into account all interactions, ensuring a more full evaluation of a website's responsiveness. By considering the latency of click, tap, and keyboard interactions, INP captures the overall user experience by identifying the longest interaction observed while ignoring outliers.
The calculation of the INP score involves measuring the duration of event handlers associated with an interaction, starting from the initiation of the interaction until the next frame is presented with visual feedback. The goal is to minimize this time gap and provide immediate visual feedback to users, indicating that their actions are being processed by the website.
To determine the quality of a website's responsiveness, INP scores are categorized into three thresholds:
- Good responsiveness: INP below or at 200 milliseconds.
- Needs improvement: INP above 200 milliseconds and below or at 500 milliseconds.
- Poor responsiveness: INP above 500 milliseconds.
These thresholds serve as guidelines for developers to set achievable development expectations and prioritize optimizations as a result.
Monitoring and optimizing the INP score is important for delivering exceptional user experiences. Publishers running ads should pay particular attention to INP, as ad scripts are a common source of Long Tasks that degrade responsiveness — see our guide on how ads affect Core Web Vitals. Publishers can leverage tools like Pubperf analytics, which now supports INP score measurement. Pubperf analytics provides real-time insights into INP values and other performance metrics, allowing publishers to identify slow interactions and take proactive measures to strengthen their website's responsiveness.
Measuring the INP score can be done both in the field and in the lab. Field data obtained through Real User Monitoring (RUM) provides helpful information about specific interactions responsible for the INP score, allowing developers to pinpoint areas that require optimization. Additionally, Chrome User Experience Report (CrUX) offers origin-level and page-level INP data for websites that qualify.
In the lab, developers can reproduce slow interactions by following common user flows and testing interactions during important stages of page loading. By combining field data insights with lab testing, developers gain a complete understanding of slow interactions and can implement optimizations effectively.
Improving the INP score involves several strategies, such as optimizing event handler performance, reducing main thread workload, and prioritizing major rendering paths. The process requires a thorough look at the specific interactions causing delays and addressing performance bottlenecks accordingly.
The INP score is a critical metric for assessing a website's responsiveness and optimizing user experiences. Since Core Web Vitals are now a Google ranking factor, a strong INP score also supports your search visibility. With Pubperf analytics now supporting INP score measurement, publishers have a powerful tool at their disposal to monitor and fine-tune INP. By prioritizing performance enhancements based on INP insights, web developers can deliver highly responsive and interactive websites, resulting in improved user satisfaction and engagement.
INP is now a Core Web Vital ranking factor. Pubperf monitors your INP scores across all pages and identifies the Long Tasks dragging down your responsiveness.