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To improve Interaction to Next Paint (INP), start with real-user field data, identify an interaction that is slow for users, reproduce it in Chrome DevTools, and use the trace to determine whether the delay comes from main-thread contention, event-handler work, or rendering. Make a targeted change, retest the same interaction, and monitor field results to see whether the improvement reaches users.
What INP measures—and what counts as good
INP measures responsiveness across qualifying interactions during a page visit. Rather than judging a page only by its first input, it reports a value that represents how quickly the page responded to all or nearly all interactions, with some outlier handling. A low INP means most interactions received a quick response.
INP became a stable Core Web Vital and replaced First Input Delay (FID) on March 12, 2024. FID covered only the delay before the first event handler began; INP considers responsiveness throughout the visit.
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Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →| INP at the 75th percentile | Assessment |
|---|---|
| 200 ms or less | Good |
| Above 200 ms and through 500 ms | Needs improvement |
| Above 500 ms | Poor |
Assess the 75th percentile separately for mobile and desktop. That percentile means at least 75% of measured page loads in the segment have an INP at or below the reported value; it is not a guarantee that every visit or interaction meets the threshold. Field results reflect the users and page loads represented in the data.
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The web.dev INP guide reports, attributing the figure to Chrome usage data in its 2025 update, that “90% of a user’s time on a page is spent after it loads.” That is a useful reminder to evaluate responsiveness after initial loading, not a claim that every site has the same usage pattern.
How to find out whether users have an INP problem
Start with field data
Check PageSpeed Insights for Chrome User Experience Report (CrUX) data on the page or origin, if it is available. Search Console’s Core Web Vitals report can also show field performance for covered sites. These sources help establish whether real-user experience is poor and whether mobile, desktop, or both need attention.
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CrUX is aggregated field data, not an interaction trace. It can show that INP is a problem without identifying the particular control, user flow, or event handler responsible. Data may be unavailable for pages or origins that do not meet CrUX eligibility requirements, and CrUX results can differ from a site’s own real-user monitoring (RUM) because the sources may cover different populations and aggregate data differently.
Use RUM when aggregate data is not enough
RUM collects performance data from visits to your own site. An appropriately instrumented setup can capture more diagnostic context than an aggregate CrUX value, such as which interaction was slow and what was happening around it. Interaction-level RUM or the attribution build of the web-vitals JavaScript library can help connect a field problem to a page and interaction. The Long Animation Frames (LoAF) API can provide additional context for slow interactions when it is supported and used in an appropriate instrumentation setup.
Rank #3
Choose RUM when you need to diagnose a recurring field issue that aggregate reporting cannot localize. It adds instrumentation and data-handling work; it does not make a local trace unnecessary when you need to inspect the code path.
Know what each measurement can establish
| Measurement option | What it helps answer | What it cannot establish by itself |
|---|---|---|
| PageSpeed Insights with available CrUX data | Whether field data indicates an INP issue for a page or origin. | Which exact interaction or handler caused the result. |
| Search Console Core Web Vitals report | Whether covered site data shows Core Web Vitals performance issues. | The detailed execution sequence behind a slow interaction. |
| RUM or interaction-attributed web-vitals data | More context about slow interactions experienced by the instrumented site’s users. | A reproducible local trace of the code and rendering work for every affected case. |
| Chrome DevTools Performance recording | What happened during a specific interaction in the recorded local flow. | How all real users experience the page in the field. |
How to reproduce a slow interaction in Chrome DevTools
- Choose a field-relevant flow. Use RUM attribution where available, or narrow the issue to a page and user journey indicated by field data. Avoid choosing a convenient interaction that does not represent the observed problem.
- Open the Performance panel. In Chrome DevTools, start a recording, perform the interaction under investigation, then stop the recording.
- Inspect the Interactions track. Expand the track and select a slow interaction. Examine the event timing and the main-thread activity around it to see where the delay accumulated.
- Repeat under realistic conditions. Record the relevant flow again if needed, and note the conditions and interactions exercised. A local lab recording only describes that recording; it does not prove a field-wide improvement.
The official INP codelab uses a deliberately long synchronous block in an event listener to make processing duration visibly increase. That is a teaching demonstration for understanding a trace, not evidence that any particular production site has the same problem.
How to read the three parts of an INP interaction
Use the interaction breakdown to locate the work that precedes the next visual update. An interaction’s delay can be understood as three stages:
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Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →- Input delay: the time from the user’s input until the relevant event callbacks begin. Other work occupying the main thread can prevent those callbacks from starting promptly.
- Processing duration: the time spent executing the relevant event callbacks. A slow handler points toward work performed in response to the event.
- Presentation delay: the time the browser takes to produce the next frame containing the visual update. A late frame can point toward expensive rendering or presentation work after callbacks run.
These stages are diagnostic clues, not interchangeable labels for the same problem. A long input delay calls for examining what was already occupying the main thread. A long processing duration directs attention to callback work. A long presentation delay directs attention to the rendering and visual update that follows. Confirm the suspected cause in the trace before changing code.
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What to change after you identify the bottleneck
If input delay is high, reduce main-thread contention
Look for JavaScript work that runs before the interaction’s callbacks can begin. Remove JavaScript that is not needed, and break up long-running tasks so they do not monopolize the main thread. The specific task to defer, split, or remove depends on what the recording shows; a generic optimization is not proof of an INP fix.
If processing duration is high, do less in the handler
Keep event callbacks focused on the work needed to respond. Avoid doing unnecessary JavaScript in response to input, and split work that would otherwise run as one long task. The goal is not merely to shorten a particular function in isolation: verify that the interaction’s processing interval gets shorter in the trace.
If presentation delay is high, limit the rendering work
Inspect the work that produces the visual response. Avoid large rendering updates when a smaller update can provide the needed feedback, and investigate expensive rendering activity visible around the next frame. The appropriate change depends on the page’s trace and should be validated with the same interaction.
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How to verify that an INP change helped
- Record the same interaction again. Compare the relevant interaction and its input-delay, processing-duration, and presentation-delay portions before and after the change.
- Check for trade-offs. Confirm the visual response still does what users need and that shifting work has not simply moved the delay elsewhere in the flow.
- Watch field outcomes. Continue monitoring the affected page or origin in field data, segmented by mobile and desktop. Use RUM attribution where available to check whether the interaction that motivated the change improved for users.
A DevTools recording verifies behavior under the conditions you recorded; it does not establish that every user’s INP improved. Field monitoring is needed to confirm whether the change persists in real visits.
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