Since Google introduced Core Web Vitals as a ranking signal, they've been relevant for every website that wants to be found via search engines. In 2026, the framework has evolved – and the requirements have become stricter.
What Has Changed: INP Instead of FID
The biggest change: Interaction to Next Paint (INP) has fully replaced First Input Delay (FID). While FID only measured the response time to the first interaction, INP evaluates responsiveness across the entire page session. This is stricter but more realistic: a page that responds quickly on the first click but stutters on subsequent interactions is now correctly penalised.
The three metrics in 2026 are: Largest Contentful Paint (LCP) – under 2.5 seconds, Interaction to Next Paint (INP) – under 200 milliseconds, Cumulative Layout Shift (CLS) – under 0.1.
The Most Common Problem Causes
Poor LCP: Usually caused by unoptimised hero images (no WebP/AVIF, no lazy loading for above-the-fold content), render-blocking CSS/JS or slow server response time (TTFB). Solution: serve images in next-gen formats, inline critical CSS, implement server-side rendering or caching.
Poor INP: Often caused by heavy JavaScript blocking the main thread. Every time a user clicks while the browser is still busy with a script, the INP value rises. Solution: split JavaScript bundles, lazy-load third-party scripts, use Web Workers for computationally intensive tasks.
Poor CLS: Images without defined dimensions, ads that load after the page, or fonts that shift text. Solution: always set width/height on images, use font-display: swap, reserve placeholders for dynamic content.
Three Quick Wins That Work Immediately
First: check your website with PageSpeed Insights and identify the three biggest opportunities. Second: compress and convert all images to WebP or AVIF – this reduces file size by 50–80%. Third: remove unused plugins and scripts. Every WordPress plugin that loads its own CSS and JavaScript degrades INP and LCP.
Core Web Vitals aren't a one-off project – they require ongoing monitoring. Google Search Console shows you the values for your entire website. Set up monthly reports and respond before yellow values turn red.
Want to professionally optimise your Core Web Vitals? Sidora AG conducts technical performance audits and implements the measures directly. Request an audit now.
