What is Interaction to Next Paint?
A Google Core Web Vitals metric that evaluates a webpage’s overall responsiveness by measuring the latency of all user interactions (clicks, taps, and keyboard inputs) throughout the visit.
Replacing First Input Delay (FID)
While legacy FID evaluated only the initial click of a visit, INP observes all user interactions throughout the full lifespan of a page. INP represents the longest interaction latency observed (excluding rare outliers).
An interaction is broken into three phases: Input Delay (waiting for background tasks to finish), Processing Time (executing JavaScript event callbacks), and Presentation Delay (browser recalculating layout and painting pixels).
Eliminating Main-Thread Long Tasks
Any JavaScript task taking longer than 50 milliseconds blocks the main browser thread, preventing the UI from responding to user clicks and driving INP into the "Poor" zone (>500ms).
DocSwift maintains near-zero INP by shifting heavy PDF compression, image parsing, and cryptography algorithms into dedicated Web Worker threads, allowing the main thread to paint frame updates in under 16ms.
Key Advantages & Impact
- Direct Google search ranking factor affecting organic search visibility and mobile traffic
- Provides realistic measurement of user frustration and UI lag across complex web applications
- Encourages clean frontend architecture by separating CPU computation from DOM rendering
Common Misconceptions vs Reality
Experience This Technology in DocSwift Tools
Frequently Asked Questions
What is a "Good" INP score according to Google?
An INP of 200 milliseconds or less represents good responsiveness. Between 200ms and 500ms needs improvement, and over 500ms is poor.