Core Web Vitals are a set of three page-experience metrics published by Google to quantify how a page feels to load and use. They are Largest Contentful Paint (LCP), which measures how quickly the main content of a page becomes visible; Cumulative Layout Shift (CLS), which measures how much the page jumps around as it loads; and Interaction to Next Paint (INP), which measures how responsive the page is when a visitor taps, clicks, or types. INP replaced the older First Input Delay metric in March 2024.
I treat Core Web Vitals as a floor, not a target. Hitting the green thresholds (LCP under 2.5s, CLS under 0.1, INP under 200ms) is the price of admission for a modern site. They're a small ranking factor on their own, but they correlate strongly with bounce rate and conversion, which makes them worth fixing for reasons that have nothing to do with SEO.
The most common LCP problems I see on WordPress sites are unoptimized hero images, render-blocking JavaScript from analytics or chat widgets, and slow time-to-first-byte from a host that's run out of headroom. CLS problems usually come from images without dimensions, ads that inject mid-page, or web fonts that swap visibly. INP problems usually come from heavy JavaScript that runs on every interaction — over-eager analytics scripts, a page builder's runtime, or a third-party widget bundle.
The fix for most sites is unglamorous: serve images in WebP or AVIF with explicit width and height, defer non-critical scripts, and audit plugins for ones that load on every page when they only need to load on a few.
