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.

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.

What should alt text say?

Describe what the image shows, for someone who cannot see it. If the image is a link, describe where the link goes. If it is purely decorative, use an empty alt attribute so screen readers skip it — but never omit the attribute entirely.

Performance

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.

Answered by Anas Bin Masud 151 words 3 sections

The formats and where each belongs

Format	Use for	Note
AVIF	Photographs	30–50% smaller than WebP, slower to encode
WebP	Photographs, fallback	25–35% smaller than JPEG, universally supported
JPEG	Final fallback	Universally supported
PNG	Images needing transparency without WebP	Large; usually avoidable
SVG	Logos, icons, line art	Scales infinitely, tiny, no variants needed

The bigger saving

Sizing. Serving a 2000-pixel image to a 390-pixel phone wastes more than any format choice recovers. Generate several widths and let srcset and sizes pick.

The two attributes that must always be there

Width and height, or an aspect-ratio in CSS. Without them the page reflows as images arrive, which is measured directly as Cumulative Layout Shift.

The longer version

This answer is deliberately short. If you want the full treatment, Image SEO: findable images that do not wreck your page speed 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.