What are Core Web Vitals?

Three metrics Google uses to measure page experience: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability. They are assessed on real visitor data over a rolling 28-day window.

Why is my website slow?

Usually one of four things: unoptimised images, render-blocking CSS or JavaScript, a slow server response, or a framework executing before anything paints. Measure first — the cause is almost never what people assume, and fixing the wrong one changes nothing.

What image format should I use on my website?

AVIF first, WebP as a fallback, JPEG or PNG last, delivered through a picture element. SVG for logos, icons and line art. Getting the size right for each viewport saves more than the format choice, so do both.

Performance

How do I improve Largest Contentful Paint?

Find what is on the critical path before the largest element can paint, and remove it. Usually a render-blocking stylesheet, a late-discovered font, an oversized image, or a client-rendered page where nothing paints until a bundle executes.

Answered by Anas Bin Masud 189 words 3 sections

The sequence that works

Identify the LCP element from field data, not from your own browser
Make sure it is in the initial HTML rather than injected by script
Preload only what that element needs — one font, one image
Serve the image in a modern format at the size the viewport uses
Remove render-blocking CSS and JavaScript from the critical path
Then look at server response time, which is a constant added to everything

The two mistakes that undo the work

Lazy-loading the hero image, which adds a full round trip to your worst metric
Preloading a dozen resources, which competes for bandwidth and helps none of them

The architectural fix

If the page is the same for everyone, generate it statically. A client-rendered page puts four sequential steps between the request and the first pixel, which is how a site reaches a nine-second LCP without any single file being large.

The longer version

This answer is deliberately short. If you want the full treatment, Core Web Vitals, and the order that actually reduces them covers it in about 3 minutes — free, ungated, written from client work.

Who answered this

Anas Bin Masud builds e-commerce sites and does technical SEO for businesses in the UK, Canada and Pakistan — fifteen live client sites, six of them stores taking real payments. These answers come from those projects rather than from a content brief. More about how I work, or ask me something directly.