Core Web Vitals, in plain language
LCP, INP and CLS sound like lab equipment. They are really three simple questions about how your site feels to a person in a hurry.
Three questions behind three acronyms
Strip away the jargon and Core Web Vitals ask: does the page show its main content quickly (LCP), does it react when you tap something (INP), and does it hold still while you read it (CLS)?
Google measures these on real visitors, on their own phones and connections. Your score reflects the phone on a train, and that is exactly why the numbers often look worse than the site feels on your fibre-connected office laptop.
Where the seconds actually go
In most small-business sites the pattern repeats: a hero image saved at 4000 pixels wide, a font that blocks rendering, and a tag manager loading twelve scripts before the page draws anything. None of these is exotic. All of them are fixable in an afternoon.
Layout shift is usually even simpler. Images without width and height attributes, or a cookie banner that pushes the page down after it loads. Reserve the space, and the jumping stops.
Fix the template, and every page follows
The lucky thing about performance problems is that they live in templates. Fix the product-page template once and five hundred product pages improve together. This is why a slow site is usually two or three fixes away from a fast one, however many pages it has.
Start with the template your visitors land on most, measure again after each change, and stop when the numbers are green. Perfection past that point is a hobby, and the site gains nothing from it.