My WordPress Site Is Slow. What Should I Check First?

When someone tells us their WordPress site is slow, the first instinct is often to blame the hosting and upgrade. Sometimes that's right. Far more often, the site would be slow on any server, because of something inside WordPress itself.

Here's the order we go through it. It's roughly from most likely to least likely.

1. Measure it first

"Slow" is a feeling, and feelings are bad at diagnosis. Run the site through a proper test, on mobile, so you've got a number to compare against later. Our free speed check does this and tells you in plain English which bits are heavy. Write the score down before you change anything.

Test a couple of pages, not just the home page. A slow shop page and a fast home page point to very different problems.

2. Images

This is the big one. A phone photo straight off the camera can be 4 or 5 MB. Put six of those in a gallery and you've got a page that would take ages on a good connection, never mind 4G in a car park.

• Resize images to the size they're actually shown at. A picture displayed 800 pixels wide doesn't need to be 4,000 pixels wide.
• Use WebP where you can. WordPress supports it.
• Make sure lazy loading is on, so images further down the page only load when someone scrolls to them.

3. Caching

Without caching, WordPress builds every page from scratch for every visitor. It runs PHP, asks the database for the content and assembles the page, every time. Caching saves the finished page and hands that out instead.

Our servers run OpenLiteSpeed, so the plugin you want is LiteSpeed Cache. Install it, switch on page caching, and test again. Don't stack it with a second caching plugin. Two caches fighting each other is a common cause of odd behaviour.

4. Plugins

It isn't really the number of plugins that matters. It's what they do. Twenty small, well-written plugins can be fine. One badly written slider can wreck a page.

Go through your list and ask of each one: do I still use this? Anything you're not sure about, deactivate it, and test again. Common heavy hitters are sliders, social feeds, "all-in-one" security suites, and statistics plugins that store every visit in your database.

5. The theme or page builder

Some themes load a huge amount of code on every page, including features you've never touched. Page builders vary a lot too. If you've ruled out images, caching and plugins and the site is still sluggish, the theme is the next suspect. Switching theme isn't a small job, so get the cheaper fixes done first.

6. Things loaded from other websites

Chat widgets, embedded maps, booking widgets, tracking scripts, fonts from three different places. Each one is another trip to another server, and you can't control how fast any of them answers. Keep the ones that earn their place and drop the rest.

7. PHP version

Newer versions of PHP are noticeably faster than old ones. In your control panel you can choose PHP per site. If you're on something old, move up, then check the site still works properly. If something breaks, switch back and let us know. It usually means an out-of-date plugin.

8. Then, and only then, the hosting

If you've been through all of the above and pages are still slow before anything has loaded, the server may genuinely be the bottleneck. Busy shops with lots of logged-in customers can outgrow a small plan. That's when it's worth talking about more resources, and we'll tell you honestly whether it'll help.

If you'd rather not do any of this yourself, it's exactly the sort of job we do. Send us the address and we'll tell you what we'd change first.