Core Web Vitals: what actually moves the needle

Teams spend weeks shaving kilobytes off JavaScript while a single unoptimised hero image quietly owns their Largest Contentful Paint.

The three that matter

First, whatever renders largest above the fold. Usually a hero image or heading. Serve it in a modern format, at the right dimensions, and never lazy-load it.

Second, layout shift from images and embeds without reserved dimensions. Width and height attributes cost nothing and fix most of it.

Third, third-party scripts. Every tag manager container, chat widget and analytics script competes with your content for the main thread.

Fix those three before touching anything else.