Google's Core Web Vitals — the performance metrics that feed into rankings — have a newer member that most website owners have never checked: INP, Interaction to Next Paint. Where the old FID metric measured only the first input delay, INP measures the responsiveness of every tap and click across the whole visit, and reports one of the slowest. The bar: under 200 milliseconds.

Here is the uncomfortable part: heavy WordPress themes, page builders stacked with plugins, and script-laden templates routinely score 400–800ms. Your site can look fast and still fail INP, because the metric captures what happens when users interact — open the menu, tap a filter, submit a form — not just how quickly pixels first appear.

What Causes Bad INP

  • JavaScript bloat. Every plugin, tracker, chat widget and slider ships script that competes for the main thread. When a user taps during that congestion, the browser cannot respond.
  • Long tasks. Any script chunk that runs longer than 50ms blocks interaction. Analytics bundles and poorly-written theme code are the usual offenders.
  • Layout thrash. Handlers that force style recalculation on every scroll or input event.
  • Third-party embeds. Social feeds, map embeds and video players that inject their own script mountains.

Fixes That Actually Work

Remove before optimising. The fastest JavaScript is deleted JavaScript — audit plugins and trackers ruthlessly; most sites carry passengers nobody remembers installing. Defer what remains so scripts load after content, and lazy-load embeds only when scrolled into view. Break up long tasks and debounce input handlers. And structurally: server-rendered pages with minimal client script — the architecture we use on every build — start with INP headroom that plugin-stacked sites can never recover.

Check Yourself Today

Run your site through PageSpeed Insights and look for the INP field under "Core Web Vitals Assessment" — that is real user data, not a lab simulation. If you are failing, you are conceding rankings to faster competitors every day. Slow enough to annoy users is now slow enough to lose customers twice: once to the back button, once to the algorithm. Our web development team builds and rescues sites to pass these thresholds as a baseline, not an upsell.