Page speed and Core Web Vitals

Visitors are impatient. If a page takes more than a few seconds to load on mobile, a large share leave before reading a single word. Google knows this, and takes user experience into account when assessing your pages. The main yardstick for that is the Core Web Vitals.

What do Core Web Vitals measure?

• LCP (Largest Contentful Paint): how quickly the largest visible element, often the main image or heading, appears. Aim for under 2.5 seconds.
• INP (Interaction to Next Paint): how quickly the page responds when someone clicks or types. Under 200 milliseconds is good.
• CLS (Cumulative Layout Shift): how much the page jumps around while loading. You know the feeling: you go to tap a button and suddenly everything shifts down.

What Obelisk takes care of

The technology beneath your site, such as hosting, a secure connection via SSL and building the pages, isn't something you have to set up yourself. What you do control is what you put on a page. In practice, that's also where the biggest gains are.

Choices that keep your site fast

• Lightweight images. By far the biggest factor. See the tips on images.
• Be sparing with external scripts. Every chat widget, ad pixel or extra tracking code loads code from another server. Only use what you really need; see also external scripts and widgets.
• Choose a lightweight analytics solution if you only want visitor numbers. A cookieless package also saves you the consent prompt; read more in analytics.
• Background video in moderation. Lovely at the top of the homepage, but heavy if it's on every page.
• Give images and embeds fixed dimensions, so the page doesn't jump around while loading.

How to measure it

Enter a page in Google PageSpeed Insights. You'll get the Core Web Vitals for mobile and desktop, with concrete pointers. Focus mainly on the mobile score: Google primarily assesses your site on its mobile version. In Search Console you can also see which pages across your whole site are flagged as slow.

A concrete example

A restaurant had a slider on its homepage with eight photos of 4 MB each, a chat widget and three tracking scripts. Mobile LCP was over 7 seconds. After resizing the photos, removing one redundant script and replacing the slider with a single strong hero photo, it dropped below 2.5 seconds. Reservations through the site rose noticeably.

Common mistakes

Only testing on a fast office connection, leaving scripts in place for services you no longer use, and loading every page with animations. Speed isn't a one-off job: after every major change, quickly check your most important pages.