01 / First, measure
Guessing is how people spend money on the wrong fix
Before changing anything, run the site through PageSpeed Insights and look at one number: Largest Contentful Paint. That is how long it takes for the main thing on the screen to appear. Under 2.5 seconds is fine. Over 4 is why people leave.
Test the page people actually land on, not the homepage, and test it on mobile. Your site is not slow on your laptop on office wi-fi. It is slow on a four-year-old Android on a train.
02 / The usual culprit
Images, almost every time
The most common cause of a slow WordPress site is a 4MB photograph straight off a camera, displayed 800 pixels wide. The browser downloads all four megabytes and throws most of it away.
Three things fix it, in order of return:
- Resize before uploading. Nothing on a website needs to be 5000 pixels wide.
- Serve modern formats. WebP is typically a third smaller than JPEG at the same quality.
- Make sure responsive sizes are working. WordPress generates several sizes and offers the browser a choice, but only when the sizes share an aspect ratio. A theme with one custom crop and nothing to match it silently serves the largest file to every phone. We found exactly that on our own site recently.
03 / The second culprit
Plugins you forgot you installed
Every active plugin can add CSS and JavaScript to every page, whether or not the page uses it. A slider plugin used on the homepage often loads on all forty pages.
Open your plugin list and ask of each one: do we still use this? Deactivating what you do not need is the cheapest performance work there is, and it reduces your security exposure at the same time. Be sceptical of anything that promises to “optimise” by adding another plugin.
04 / The third
Hosting that costs three pounds a month
Cheap shared hosting puts hundreds of sites on one machine. When the others are busy, you are slow, and no amount of tuning on your side changes that. If your time-to-first-byte is above about 600ms consistently, the problem is under the site rather than in it.
You do not need enterprise hosting. You need a host that is honest about what you are sharing.
05 / The fourth
Caching, done once, properly
Without caching, WordPress rebuilds every page from the database on every visit. A page cache stores the finished result and serves that instead. On a site whose content changes daily rather than hourly, this is the single biggest win after images.
One caching plugin. Not three. They conflict, and the debugging costs more than the milliseconds.
06 / What not to bother with
Two things that get sold as fixes and are not
Chasing a score of 100. The difference between 85 and 100 is invisible to a customer. The difference between 30 and 85 is the whole business case. Stop at good.
Minification as a first move. Compressing your CSS saves kilobytes. Fixing one image saves megabytes. Do the big one first.
Send us the URL and we will tell you which of the four is costing you the most, including when the honest answer is that your site is already fast enough.