The Complete Guide to Optimizing Interaction to Next Paint (INP) & Core Web Vitals

Interaction to Next Paint (INP) is Google's Core Web Vital metric measuring responsiveness across the entire lifecycle of a user session. A poor INP score directly harms your Google search ranking and degrades customer conversion rates.

What Causes High INP?

INP measures the time between a user interaction (click, keypress, tap) and the moment the next frame is rendered to the screen. The primary culprits are:

• Long Tasks (> 50ms): Heavy JavaScript execution blocking the browser main thread.
• Excessive DOM Relayout: Triggering layout thrashing by reading and writing layout properties consecutively.
• Unoptimized Event Handlers: Running non-urgent computations synchronously inside click handlers.

How BugSpray Pinpoints INP Spikes

BugSpray automatically captures Performance Long Tasks and links them directly to the user session video. You can see the exact click that caused the delay, the call stack responsible, and the frame drop visualization.