How to Speed Up a WordPress Site: A Practical Optimisation Checklist for Core Web Vitals

Core Web Vitals are Google’s way of measuring real-world user experience on your WordPress site.

Core Web Vitals are linked to your actual rankings in Google and are an easy way to judge user experience on your site.

What Are Core Web Vitals?

These are specific metrics Google uses to check the quality of user experience on web pages.They focus on three things: how quickly your main content loads, how stable the page is during loading, and how fast your site reacts to user actions.Google built these metrics to create a unified way to measure site performance. Unlike old-school speed tests that just look at technical stuff, Core Web Vitals reflect what real visitors experience when they browse your site.They’re part of Google’s bigger page experience signals. Alongside things like mobile-friendliness and HTTPS, they carry a lot of weight in how Google judges your site’s quality.

The Role of Core Web Vitals in SEO and User Experience

Core Web Vitals are now a ranking factor in Google’s search algorithm. If your site hits the recommended targets, you might get a rankings boost. If not, you could see your visibility drop.These metrics also tie directly to user satisfaction. If your site isn’t meeting the requirements, it’s a sign that your pages are loading slowly, which can lead to user frustration.

LCP, INP, and CLS Explained

The Core Web Vitals rely on three things – LCP, INP, and CLS.

You don’t need to know exactly how each of these work, but here’s a quick summary of them:

• Largest Contentful Paint (LCP) measures how long it takes for your main content – like big images, video, or text – to show up. Google says you want LCP at 2.5 seconds or less.
• Interaction to Next Paint (INP) replaced First Input Delay in March 2024. It tracks how quickly your site responds visually after a user interacts, like clicking a button. Aim for under 200 milliseconds here.
• Cumulative Layout Shift (CLS) measures how much stuff moves around unexpectedly as the page loads. Things like images or ads shifting the layout are a no-go. A CLS score below 0.1 is considered good.

Again, these numbers are important to memorise. What is important is to implement best practices that keep all of these numbers as low as possible, so your site loads quickly and keeps users happy.

To really understand your WordPress site’s performance, you need both real-world user data and controlled tests.

Google Search Console and PageSpeed Insights each show different sides of the story.

Using PageSpeed Insights

PageSpeed Insights mixes lab data from Lighthouse with real user data. Plug in your URL, and you’ll get scores for both mobile and desktop, plus details for LCP, FID, and CLS.The tool sorts your performance as ‘Good’, ‘Needs Improvement’, or ‘Poor’, based on Google’s thresholds. Lighthouse runs in a controlled setup, so you get consistent results to track your progress.

Now that we know how to monitor how fast our WordPress site is loading, it’s time to look at the ways you can speed it up.

The first thing to look at is hosting, as this can make a really big difference in how fast your website loads.

Choosing the Right Hosting Provider

Choosing a hosting provider is a challenge in itself.Some tips for this include:

• Choose a reputable hosting service
• Choose a hosting service that supports WordPress
• Extra bonuses include CDNs and non-shared hosting accounts

If you go straight for the cheapest option, you’ll likely find yourself with a shared hosting server that loads slowly.

Consider Managed WordPress Hosting

Managed WordPress hosting is built specifically for WordPress. It comes with extra features like built-in caching, automatic updates, and staging sites for safe testing.The real advantage is the server-level optimisation. Managed hosts usually handle object caching, opcache, and database tweaks automatically.Most managed providers throw in a CDN, which stores your static files (images, CSS, JavaScript) in multiple locations worldwide. That means faster loads for visitors from anywhere.Shared hosting is more expensive, but it’s a really good option if you want to cover most bases without getting technical.

The next thing to look at is the theme you are running, as well as any plugins or scripts that are used.

The general idea here is that less is more. Keep your theme lightweight, avoid unnecessary plugins and scripts, and your site will load much faster and be more reliable.

Selecting Lightweight WordPress Themes

Your theme sets the baseline for performance. In other words, it’s very hard to make a clunky theme load fast.Pick themes built for speed. Look for ones with clean HTML, minimal CSS, and as little JavaScript as possible. GeneratePress, Astra, and Kadence are great options.Custom themes are also an option, but these require an expert setup. This is something that we help our clients with.

Auditing and Deleting Unused Plugins

Every plugin adds code that WordPress has to load.Even inactive plugins can eat up resources, and active ones you don’t need just slow things down for no reason.Make sure to check your plugins to see which ones are actually being used and which ones aren’t. Get rid of any that are not being used, and look for lighter alternatives to your existing plugins where possible.

Third-Party Scripts

Third-party scripts – think analytics, ads, social widgets, chatbots – often make up most of your JavaScript. They run on the main thread and can create long tasks that hurt your interaction scores.Use Chrome DevTools to audit all external scripts. Figure out which ones are hogging resources and decide if you really need them.

Next up is image optimisation.

Images make up a huge portion of most web pages’ file size, which is why optimising them makes most websites load faster instantly.

Compressing and Converting Images (WebP, AVIF)

Modern image formats like WebP and AVIF can shrink file sizes a lot without making things look worse.WebP usually gives you 25-35% smaller files than JPEG, and AVIF can push compression even further – sometimes cutting size by half for the same quality.WebP is the best choice in most cases, and this can easily be done by using an image compression tool.

Enabling Lazy Loading for Images

Lazy loading means images off-screen don’t load until someone scrolls near them. This cuts down initial page weight and helps your site feel faster.Fortunately, WordPress has native lazy loading since version 5.5, which adds loading=”lazy” to images by default. Still, double-check your theme isn’t switching this off behind the scenes.

Setting Proper Image Dimensions

Explicit width and height attributes stop images from causing layout jumps as they load. This directly helps your Cumulative Layout Shift (CLS) score. WordPress usually adds these automatically if you upload through the media library.Even if you’re using CSS for sizing, you still need to specify dimensions in your HTML. That way, browsers know how much space to reserve before the image appears.

Render-blocking CSS and JavaScript force browsers to wait before painting your page. Tackling minification, optimising rendering, and preloading the right assets can give your Core Web Vitals scores a real boost.

Minifying and Combining CSS and JavaScript

Minification strips out stuff like whitespace, comments, and extra formatting from your code. This makes files smaller and faster to download.Most caching plugins do this for you. WP Rocket has a one-click minify option for CSS and JavaScript, while W3 Total Cache lets you pick which files to minify. Both can combine multiple CSS or JS files, cutting down on HTTP requests.But don’t get too aggressive with combining files. Some plugins and themes need scripts in a certain order, so test everything after making changes.Also, turn on browser caching in your plugin or server settings. This tells browsers to keep static files locally, so repeat visitors aren’t re-downloading the same stuff.

Optimising Client-Side Rendering

Client-side rendering happens when JavaScript builds your page in the browser instead of serving pre-made HTML. Too much of this delays content and hurts your Largest Contentful Paint (LCP) score.Defer non-critical JavaScript so it doesn’t block the initial render. Most performance plugins let you do this, or you can add the defer attribute to scripts that aren’t urgent.If a script needs to load early but doesn’t block rendering, use async instead. That lets the script load alongside the rest of the page.Hold off on loading JavaScript for things like chat widgets or social embeds until users interact. WP Rocket’s delay JavaScript feature can help here, and it makes a noticeable difference.

There are some more advanced tools you can use to speed up your WordPress site and monitor the changes in load speed.

Implementing a CDN for Global Delivery

A content delivery network (CDN) spreads your site’s static files across servers worldwide. This means users can access files from the server closest to them, rather than from a single location.CDNs rely on distributed groups of servers that cache content near end users, meaning your content loads faster worldwide rather than close to one server.Keep an eye on bandwidth and cache hit rates in your CDN’s analytics. If your cache hit rate is above 85%, you’re in good shape. If not, it’s time to tweak your cache settings.

Using Accelerated Mobile Pages (AMP)

Accelerated Mobile Pages (AMP) offer a stripped-down HTML framework aimed at speed for mobile users.Google’s mobile-first indexing still gives some weight to fast-loading mobile experiences, so AMP can matter for content-heavy sites after organic traffic.This is generally only recommended for large news websites, and not something we would recommend to the average client WordPress site.

We hope this guide has given you a good starting point for speeding up your WordPress site.At Identify Digital, we always design and develop WordPress sites for clients with speed in mind, ensuring the websites load quickly and satisfy users.If you need help with your site, don’t hesitate to get in touch, and we can help to optimise your WordPress website within weeks.