Core Web Vitals

The three Core Web Vitals measure how a page feels to real users: Largest Contentful Paint (LCP) measures when the largest visible element has loaded (target: under 2.5 seconds). Interaction to Next Paint (INP) measures how quickly the page responds to input (target: under 200 milliseconds). Cumulative Layout Shift (CLS) measures how much content jumps around while loading (target: under 0.1).

For merchants, Core Web Vitals count twice: they are a Google ranking factor and they correlate directly with conversion rate, because slow, shifting pages cost sales — especially on mobile. They are measured with real user data (field data, e.g. the Chrome UX Report) and lab tests such as PageSpeed Insights or Lighthouse.

In Shopify stores, the most common culprits are too many apps injecting their own scripts, unoptimized images, bloated themes and render-blocking third-party tags. A lean theme, a rigorous app cleanup and lazy loading usually achieve more than micro-optimizations.