INP or Interaction to Next Paint is a Core Web Vitals metric introduced by Google that measures how quickly a website responds to user interactions such as clicks, taps or key presses. For WordPress and WooCommerce stores, a strong INP score ensures smooth product browsing and frictionless checkout experiences.

Beginner explanation

When a visitor clicks Add to Cart on your WooCommerce store, they expect something to happen instantly. If the button feels slow or unresponsive, trust drops immediately.

INP measures how fast your website reacts after a user interacts with it. This includes:

  • Clicking Add to Cart
  • Opening product variations
  • Filtering products
  • Typing into checkout fields

If there is a delay between the click and the visible result, your INP score suffers. On a WooCommerce store, slow interactions can lead to frustration, cart abandonment and lost revenue.

For most stores, a good INP score is under 200 milliseconds. Anything higher can make your shop feel sluggish, especially on mobile devices.

Advanced explanation

Technically, INP measures the latency of all user interactions during a session and reports the longest interaction observed. It evaluates the time between user input and the next visual update on screen.

In WordPress and WooCommerce environments, INP is often affected by:

  • Heavy JavaScript execution
  • Cart fragments and AJAX requests
  • Third party tracking scripts
  • Page builders with excessive DOM elements
  • Poor PHP worker allocation

WooCommerce relies heavily on JavaScript for cart updates, variation selectors, dynamic pricing and checkout validation. If scripts block the main thread or execute inefficiently, interactions become delayed.

Improving INP for WooCommerce usually involves:

  • Reducing unused JavaScript
  • Deferring non critical scripts
  • Limiting third party apps
  • Upgrading hosting for better PHP processing
  • Optimising theme and plugin architecture

As a WooCommerce performance agency, we focus not only on load speed but also on interaction speed, because smooth user experience directly impacts conversion rate.

Industry context

INP replaced First Input Delay as a Core Web Vitals metric. It reflects real world user responsiveness rather than just initial input delay.

For e-commerce stores, responsiveness is critical. Customers interact with filters, dropdowns, payment fields and account areas. A store that feels slow during interaction often converts worse, even if the initial page load is fast.

Google uses field data from real users to evaluate INP performance. This means WooCommerce stores with heavy scripts or poor hosting setups may lose competitive advantage in search results.

High performing WooCommerce brands treat INP optimisation as part of ongoing development and maintenance, not as a one time technical fix.

Important links

Frequently Asked Questions

What is a good INP score for WooCommerce?

A good INP score is under 200 milliseconds. Scores between 200 and 500 milliseconds need improvement and anything above 500 milliseconds is considered poor.

Why is my WooCommerce store slow when clicking Add to Cart?

This is often caused by heavy JavaScript, slow hosting,or overloaded plugins that delay the browser from updating the screen.

Does hosting affect INP?

Yes. Slow server response and limited PHP workers can delay dynamic processes such as cart updates and checkout validation.

Can too many plugins hurt INP?

Yes. Every additional plugin can add scripts and processing overhead. Reducing unnecessary plugins often improves responsiveness significantly.