INP Is the Core Web Vital That's Secretly Killing Your WordPress Conversions (Fixes That Work)

TL;DR

Core Web Vitals are INP, LCP, and CLS. INP replaced FID for responsiveness, and Google's tools and reporting use it for Core Web Vitals evaluation. If your WordPress site "feels slow" even though it loads fine, INP is likely the culprit.

The Greg-Style Take

Most WordPress speed work is diet culture: "optimize images" and hope you feel better.

INP is different.

INP is: "When a human clicks… does the site respond like it's awake?"

What INP Actually Is (Plain English)

INP — Interaction to Next Paint — measures responsiveness to user interactions. Every time someone clicks a button, taps a menu, or types in a field, INP tracks how long it takes for the browser to visually respond.

Google's documentation positions Core Web Vitals as real-world user experience signals, and recommends achieving good CWV scores. The threshold: under 200ms is good, over 500ms is poor.

The 3 Buckets That Usually Fix INP on WordPress

Bucket 1: Too Much JavaScript

Common offenders:

• Popup/slider plugins

• Heavy analytics stacks (multiple tracking scripts)

• Chat widgets loading on every page

Fix:

• Remove what you don't need

• Load scripts only where used (don't run checkout scripts on the blog)

• Defer non-critical JavaScript

Bucket 2: Third-Party Scripts Fighting Each Other

Every third-party script (ads, analytics, chatbots, social embeds) competes for the browser's main thread. When they all fire at once, user interactions get stuck in a queue.

Fix:

• Delay non-critical scripts (load on user interaction, not page load)

• Reduce tag manager chaos — audit what's actually running

Bucket 3: "Optimization" Plugins Over-Optimizing

Ironic but true: some performance plugins make INP worse by aggressively combining/minifying JS into one massive file that blocks the main thread.

Fix:

• Undo aggressive minify/combine settings if they increase input lag

• Test before and after with real INP measurements

How to Measure (Without Becoming a Performance Engineer)

• Use PageSpeed Insights — it shows your INP score with field data from real users

• Check Search Console → Core Web Vitals for site-wide trends

• Google evaluates CWV at the 75th percentile — meaning 75% of your visits need to pass, not just the average

FAQ

Do Core Web Vitals affect rankings?

Google documentation says CWV are used by ranking systems and recommends achieving good CWV for search success.

If I get perfect scores, will I rank #1?

No — Google explicitly says good report results don't guarantee top rankings. Content relevance still dominates.

Is this only about mobile?

INP applies to both mobile and desktop, but mobile devices have weaker processors — so INP issues are usually worse on phones.

Want someone to handle this? Superpress includes performance optimization in every plan — we measure, diagnose, and fix Core Web Vitals so you don't have to.