In Brief
Test your current speed with Google PageSpeed Insights before making any changes
Resize images to the correct pixel dimensions before uploading, then compress them
Install a caching plugin like LiteSpeed Cache or WP Super Cache for immediate improvements
Check your theme isn’t slowing you down with old code or unused features
Keep everything updated so your site can run on the latest, fastest PHP version
Your WordPress site loads slowly. You click around, waiting for pages to appear, wondering if visitors are having the same frustrating experience.
They almost certainly are, and many of them aren’t sticking around to find out if things improve.
Research shows that 53% of mobile users abandon websites that take longer than three seconds to load. Every second of delay can reduce conversions by up to 7%. That’s potential customers walking away before they’ve even seen what you offer.
The good news is that you can probably fix this yourself.
Most WordPress speed problems come down to a handful of common issues, and the solutions are often free. This guide walks you through exactly what to do, step by step, without assuming you’re an expert.
By the end, you’ll understand why your site is slow, how to test it properly, and which fixes will make the biggest difference.
Table of Contents
Why WordPress Site Speed Matters
Your site’s loading time affects more than just user experience. Google uses speed as a ranking factor through what they call Core Web Vitals.
These metrics measure how quickly your pages load, how soon visitors can interact with them, and how stable the layout remains during loading.
Faster sites can rank higher in search results. Slower sites get pushed down where potential customers won’t find them. Your competitors with faster sites capture the traffic that should be coming to you.
Beyond rankings, speed directly impacts online sales.
Amazon reported that every 100 milliseconds of delay costs them 1% in revenue. While your site isn’t Amazon, the principle applies to every online business. Visitors expect pages to load quickly, especially on mobile devices.
When your site feels sluggish, visitors assume the rest of their experience will be equally frustrating.
How to Test Your WordPress Site Speed
Before fixing anything, you need to know where you stand. Running a speed test gives you a baseline measurement and helps identify what’s actually slowing your site down.
What Speed Tests Measure
Speed tests check individual pages, not your entire website.
Each page on your site will perform differently depending on its content, images, layout and functionality. Your homepage might load quickly while a gallery page with dozens of images really struggles.
Test several different pages to get an accurate picture.
At minimum, check your homepage, a typical blog post or content page, and any pages with lots of images or features. If certain pages feel slower when you browse them, test those specifically.
Using Google PageSpeed Insights
Google PageSpeed Insights is the most widely used free testing tool. Go to pagespeed.web.dev, enter your website address, and wait for the analysis. The tool checks both mobile and desktop performance, giving you separate scores for each.
Pay attention to the mobile score first.
Most of your visitors are probably browsing on phones, and mobile performance typically lags behind desktop. Google also prioritises mobile performance when ranking sites.
The results page shows specific issues affecting your speed, from unoptimised images to render-blocking JavaScript. Don’t feel overwhelmed by the technical language.
The fixes covered in this guide address most common problems.
What Your Scores Mean
PageSpeed Insights scores range from 0 to 100.
Scores above 90 indicate good performance. A score between 50 and 89 means there’s room for improvement. Below 50 suggests significant problems that need addressing.
Don’t obsess over achieving a perfect 100. What matters is real-world loading time for your visitors. A score in the 80s with a two-second load time serves your customers well.
GTmetrix is another useful testing tool that provides different insights. Testing with multiple tools gives you a fuller picture of your site’s performance.
Quick Wins for Faster WordPress
These changes often deliver the biggest speed improvements with the least effort. If you’re short on time, focus here first before moving on to more advanced techniques.
Install a Caching Plugin
Caching creates saved copies of your pages. Without caching, WordPress builds each page from scratch every time someone visits, which takes time. With caching, visitors receive a pre-built version that loads almost instantly.
Several excellent caching plugins are available for free. LiteSpeed Cache works brilliantly if your hosting uses LiteSpeed servers. WP Super Cache is reliable and straightforward to set up on any hosting. WP Fastest Cache offers a good balance of features and simplicity.
For those willing to pay, WP Rocket is widely considered the best option. It handles caching plus several other optimisations in one plugin, starting at around £47 per year.
After installing your chosen plugin, enable basic caching from its settings. Most plugins have a simple on/off toggle for page caching. That single setting often improves loading times by 50% or more.
You only need one Caching Plugin, don’t be tempted to install more than one.
How to Clear Your Cache in WordPress
Resize and Compress Your Images
Large oversize images are typically the biggest cause of slow WordPress sites. This is a two-step process: first resize to the correct pixel dimensions, then compress the file size.
Resize Before You Upload
Photos from your phone or camera are far larger than you need for a website.
A typical smartphone photo might be 4000 pixels wide, but your website probably displays images at 800-1200 pixels wide. That 4000-pixel image still downloads at full size even though it displays smaller, wasting bandwidth and slowing your page.
Before uploading any image, resize it to roughly the dimensions it will display at.
If your blog post images appear at 800 pixels wide, resize them to around 800-1000 pixels before uploading. Free tools like Canva, or the built-in photo editors on your computer, handle this easily.
This single habit makes more difference than any plugin. A properly sized image might be 150KB instead of 3MB. That’s a massive saving repeated across every image on your site.
Compress After Resizing
Once your images are the right size, compression reduces file sizes further without any visible quality loss.
ShortPixel, Imagify, and Smush are popular plugins that handle this automatically. Once installed, they compress new images as you upload them and can bulk-compress your existing media library.
Most compression plugins also convert images to WebP format, which modern browsers load significantly faster than traditional JPEGs. This alone can reduce image sizes by 25-35%.
The combination of proper sizing and compression often reduces total image weight by 80-90% compared to uploading raw photos.
WordPress Image Optimisation: A Complete Guide
Update Everything for Better Performance
Keeping WordPress, your plugins, and your theme updated improves both security and performance.
But there’s another reason updates matter: PHP compatibility.
PHP is the programming language WordPress runs on. Newer PHP versions process code significantly faster than older ones. PHP 8.2 and 8.3 offer substantial speed improvements over PHP 7.4, which many older sites still use.
However, you can only run newer PHP versions if your WordPress core, theme, and all plugins support them. Outdated plugins or themes often break on newer PHP, forcing you to stick with slower, older versions.
By keeping everything updated, you ensure your site can run on the latest PHP your hosting offers.
Check your hosting control panel to see which PHP version you’re using. If you’re on anything below PHP 8.1 and everything is updated, ask your host about upgrading.
Check for updates weekly in your WordPress dashboard under Updates. Consider enabling automatic updates for minor releases to stay current without constant attention.
Check Your Theme
Your theme has a bigger impact on speed than most people realise. The wrong theme can slow your site no matter how much you optimise elsewhere.
Old Themes Cause Problems
Themes that haven’t been updated for several years will be inefficient and contain outdated code.
They may use old methods that modern WordPress handles more efficiently. Worse, they might not be compatible with current PHP versions, forcing you to run slower, older PHP.
Check when your theme was last updated. If it hasn’t seen an update in one or more years, it’s likely holding your site back. Theme developers regularly optimise their code, and missing those updates means missing speed improvements.
An abandoned theme also poses security risks. If the developer has stopped maintaining it, security vulnerabilities won’t get patched. Consider switching to an actively maintained theme if yours hasn’t been updated recently.
Feature-Heavy Themes Add Weight
Many themes come packed with options, layouts, sliders, animations, and built-in page builders. Every feature adds code that must load whether you use it or not.
A theme advertising “50+ layout options” and “built-in slider” loads all that functionality on every page. If you’re only using a fraction of those features, you’re paying a speed penalty for code you don’t need.
Page builders like Elementor, Divi, and WPBakery add convenience but also significant code weight. A simple page built with a page builder can be three times heavier than the same design hard-coded into a theme.
Consider whether you actually need all those features. A lightweight theme designed for speed, paired with only the plugins you genuinely use, often outperforms a feature-packed theme by a wide margin.
Choosing a Faster Theme
If your theme is slowing you down, consider switching to one built for performance. GeneratePress, Astra, and Kadence are popular choices that prioritise speed while still offering flexibility.
Look for themes that score well in speed tests out of the box, receive regular updates, and don’t bundle features you won’t use. A good theme forms the foundation everything else builds on.
How to Update Your WordPress Theme Without Breaking Your Site
Advanced Speed Improvements
Once you’ve handled the basics, these additional steps can push your site’s performance further.
Use a Content Delivery Network (CDN)
A CDN stores copies of your site files on servers around the world. When someone visits your site, they receive files from a nearby server rather than waiting for data to travel from wherever your hosting is located.
Cloudflare offers a free CDN that works well for most small business sites.
Setting it up involves changing your domain’s nameservers to Cloudflare’s and enabling their caching. The process takes about 20 minutes and Cloudflare provides clear instructions.
Beyond speed, Cloudflare adds security features and reduces the load on your main hosting server. For a free service, it delivers remarkable value.
Minify CSS and JavaScript
Your site’s code contains spaces, comments, and formatting that make it readable for developers but increase file sizes. Minification removes these unnecessary characters, making files smaller without changing how they work.
Most caching plugins include minification features.
If you’ve installed WP Rocket, LiteSpeed Cache, or WP Fastest Cache, check their settings for minification options before adding another plugin. Enabling minification in your existing caching plugin keeps things simple and avoids potential conflicts between plugins.
If your caching plugin doesn’t include minification, or you want more control, the Autoptimize plugin handles it well.
Install it, enable the basic options, and check that your site still works correctly. Occasionally, minification causes visual glitches or broken features, so test thoroughly after enabling.
If something breaks, disable JavaScript minification first. That’s usually the culprit. CSS minification rarely causes problems.
Clean Up Your Database
WordPress databases accumulate clutter over time. Post revisions pile up, spam comments linger, and temporary data from plugins remains long after it’s needed. This bloat slows down database queries.
WP-Optimize is a free plugin that clears out this accumulated junk.
It removes old revisions, cleans up spam and trashed comments, and deletes expired temporary data. Running a cleanup every few months keeps your database lean.
The plugin can also schedule automatic cleanups if you prefer a hands-off approach.
When Hosting is the Problem
Sometimes no amount of optimisation can overcome fundamentally inadequate web hosting.
If you’ve tried everything in this guide and your site remains too slow, your hosting plan likely doesn’t have enough resources.
Cheaper shared hosting, where your site shares server resources with hundreds of other websites, often struggles under even moderate traffic. When neighbouring sites on the same server experience traffic spikes, your site slows down too.
Signs that hosting is your bottleneck include slow loading regardless of page content, timeouts during traffic peaks, and poor Time to First Byte (TTFB) scores in speed tests. TTFB measures how quickly your server responds to requests. Anything over 200 milliseconds suggests server-side issues.
Consider managed WordPress hosting if performance matters for your business.
UK-friendly providers like Cloudways, SiteGround, and Krystal offer significantly better performance than budget shared hosting, typically for £15-30 per month. The investment should pay for itself through better conversion rates, uptime and stability.
Common Speed Mistakes to Avoid
Knowing what slows sites down helps you avoid creating new problems while fixing existing ones.
Every plugin adds code that must load when your pages do. Thirty plugins mean thirty lots of extra code.
Audit your WordPress plugins regularly and deactivate anything you’re not actually using. A leaner plugin list means faster loading.
Installing image compression plugins but still uploading massive files is a common mistake.
Compression helps, but it can’t turn a 5MB photo into something web-appropriate. Always resize to the correct pixel dimensions first, then let compression plugins do the final optimisation.
Assuming your theme is fine because it looks good is another trap.
Visual appeal and performance are separate issues. A beautiful theme can still be bloated with unused code. Test your theme’s impact by checking your site speed, then temporarily activating a default theme like Twenty Twenty-Four and testing again. If your speed improves dramatically, your theme is part of the problem.
Always test after making changes. A setting that works perfectly on one site might cause problems on another. Check your pages load correctly after each optimisation.
Moving Forward
You don’t need to implement everything at once.
Start by testing your current speed to understand where you stand. Then work through the quick wins: caching, properly sized images, and updates. These alone often transform a sluggish site into something respectably fast.
If you want further improvements, evaluate your theme, add a CDN, and clean up your database. Consider your hosting situation if problems persist despite your optimisation efforts.
Speed optimisation isn’t a one-time fix.
New content, additional plugins, and theme updates can all affect performance over time. Test your site speed quarterly to catch any degradation early.
For sites where speed is business-critical, professional help is a must.
Speed optimisation services can fine-tune performance beyond what DIY efforts achieve. But for most small business sites, the techniques in this guide are enough to keep visitors engaged and search engines happy.
Frequently Asked Questions
Aim for pages to load within three seconds on mobile devices. Under two seconds is excellent. Google considers anything over 2.5 seconds for the main content (measured as Largest Contentful Paint) as slow. Use PageSpeed Insights to check your actual loading times.
Each image should suit the space it will take up. Resize images to roughly the dimensions they’ll display at. Most blog images work well at 800-1200 pixels wide. Header images might need 1600-2000 pixels. There’s no point uploading a 4000-pixel image that displays at 800 pixels. Resize first, then let compression plugins handle the rest.
Most speed plugins are safe when configured correctly. Caching rarely causes problems. Minification occasionally breaks JavaScript functionality or CSS styling. Always test your site after enabling new features and disable any settings that cause issues. Take a backup before making changes.
Test your current speed, then temporarily switch to a default theme like Twenty Twenty-Four and test again. If your speed improves significantly, your theme is contributing to the problem. Check when your theme was last updated too. Themes without recent updates often contain slow, outdated code.
Use the newest PHP version your hosting offers that’s compatible with your plugins and theme. PHP 8.1 or higher provides noticeable speed improvements over older versions. Check your hosting control panel to see your current version. Keep everything updated so you can safely upgrade PHP.
Free caching plugins work really well for most sites. LiteSpeed Cache, WP Super Cache, and WP Fastest Cache all deliver significant improvements without costing anything. Paid options like WP Rocket combine caching with other features and offer better support, but they’re not necessary for basic speed improvements.
Cloudflare’s free tier benefits most WordPress sites. It provides CDN services, basic security, and reduces server load. Setup takes about 20 minutes. The main reason to avoid it would be if your hosting already includes an integrated CDN, which might conflict.
Page builders like Elementor, Divi, and WPBakery add code weight to every page. A page built with a builder is typically heavier than the same design coded directly. They’re convenient but come with a speed trade-off. Consider whether the convenience outweighs the performance cost for your site.