Slow website speed costs you twice: visitors leave before they convert, and Google quietly ranks you lower for it. The good news is that most speed problems come from a small, predictable list of causes. Here’s what to check first.
Measure before you touch anything.
Run your homepage and your two or three most important pages through PageSpeed Insights or a similar Core Web Vitals tool. Note your Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and Interaction to Next Paint (INP) scores — these are the numbers Google actually uses for ranking. Google’s own web.dev Vitals guide is the definitive reference on what each metric means.
Fix images first — it’s usually the biggest win.
Uncompressed, oversized images are still the number one cause of slow pages. Serve images in WebP or AVIF format, resize them to the dimensions they’re actually displayed at, and lazy-load anything below the fold. If you’re pulling images from stock libraries or client uploads, our roundup of free online image editing tools is a handy starting point for compressing and resizing before upload.
Audit your plugins and scripts.
Every plugin and every third-party script (chat widgets, tracking pixels, font loaders) adds weight and, often, render-blocking JavaScript. Go through your active plugins and remove anything that’s not actually earning its keep — a bloated plugin stack is one of the most common causes of a slow WordPress site.
Get serious about caching.
Page caching, browser caching, and object caching (especially important for WooCommerce sites with dynamic pricing or stock levels) all reduce how much work your server does per visit. A good caching setup can cut load times dramatically without touching a single line of code.
Stabilise your layout to fix CLS.
Layout shift — when content jumps around as the page loads — usually comes from images or ads without reserved dimensions, or web fonts loading late and swapping in. Always set explicit width and height on images, and preload key fonts.
Choose hosting that matches your traffic.
Shared hosting that was fine for a five-page brochure site often becomes the bottleneck once you add WooCommerce, multiple languages, or real traffic volume. If your server response time (TTFB) is consistently above 500ms, hosting is usually the first thing to look at. A fast site also matters directly for conversions — see our post on ways to attract more customers to an online store for the bigger picture.
Re-test after every change.
Website speed optimisation isn’t a one-time project — a new plugin, a redesigned banner, or an unoptimised image upload can undo weeks of work. Re-run your Core Web Vitals check monthly, especially after major content updates.
If your site is scoring poorly and you’re not sure where to start, we regularly run this exact audit for clients and can tell you within a day which of these seven areas is actually costing you the most.
