On a fast connection you might not notice a heavy site. On a phone on a normal local connection, every extra second costs you visitors — and Google knows it, so a slow site also ranks lower.
What Core Web Vitals measure
Google boiled "is this site fast and stable" into three numbers:
- LCP (Largest Contentful Paint) — how long until the main content appears. Aim under 2.5 seconds.
- INP (Interaction to Next Paint) — how quickly the page responds when you tap or click. Aim under 200 milliseconds.
- CLS (Cumulative Layout Shift) — how much the page jumps around while loading. Aim near zero.
All three are measurable on any URL with free tools, and Google reports your real-user scores in Search Console.
The fixes that make the biggest difference
- Images. Usually the biggest weight on a page. Correct dimensions, modern formats, lazy loading below the fold, and never shipping a 3000px photo to display it at 400px.
- Fonts. Load only the weights you use, show text immediately with a fallback while the web font loads.
- JavaScript. Ship less of it, split it so each page only loads what it needs, and defer anything not needed for the first paint.
- Third-party scripts. Analytics, chat widgets, tag managers — each one is someone else's code slowing your page. Load them after the page is interactive, and drop the ones you do not use.
- Reserve space for images, ads and embeds so the layout does not jump (that is CLS).
We build for this from the start
Performance is not a cleanup pass at the end — it is decisions made throughout the build. Every site Codrex ships goes through a Core Web Vitals check before launch, and it is part of our SEO work on existing sites too.