The mistake: blaming the user's slow click

The mistake: blaming the user's slow click

When a button feels laggy, it's easy to assume the visitor's phone is old. Often the real cause is a long task — a chunk of JavaScript running for too long without pausing. While it runs, the browser can't respond to taps, so your INP — Interaction to Next Paint — suffers.

Think of it like someone monologuing for 200 milliseconds while you're trying to ask a question.

How to fix it:
— In PageSpeed Insights, look for Avoid long main-thread tasks.
— Break big scripts into smaller pieces so the browser can breathe between them.
— Move heavy calculations to run after the page becomes interactive.

Try this: click a button right as your page loads. If it stalls, you've found a long task blocking the thread, not a slow user.