Why is my website slow?

Measure first: you can't fix speed by guessing

Starting with "let's delete that, it's probably slowing us down" wastes time. Measure first, using PageSpeed Insights and your browser's network tab. Test on desktop and mobile, in a tab with an empty cache — your own browser may already hold the site in memory.

Three metrics sit under Core Web Vitals: how long the largest content takes to appear (LCP), how quickly the page responds (INP), and how much the layout shifts (CLS).

1. Unoptimised images

By far the most common cause. Resize each image to the largest size it is actually shown at, convert it to WebP or AVIF, and lazy-load anything below the fold. Serve smaller copies with srcset — a phone has no reason to download a 2800-pixel image.

2. Plugin and third-party script bloat

A typical WordPress site loads dozens of plugins, each adding CSS, JavaScript and requests. Delete what you don't use, keep one analytics tool, and don't load heavy widgets until the user interacts.

3. Slow or distant hosting

If the server's first response (TTFB) is slow, no on-page work rescues it. Cheap shared hosting puts hundreds of sites on the same resources, and a server far from your visitors adds latency to every request.

4. Caching turned off

Use page caching on the server and long-lived cache headers for static files. There's no reason to re-download an image or stylesheet on every visit.

5. Render-blocking CSS and JavaScript

Browsers must fetch certain files before painting. Defer non-critical JavaScript, remove unused CSS, and serve one small stylesheet where you can.

6. Badly loaded fonts

Self-host fonts in woff2 with only the weights you use, and add font-display: swap so text isn't invisible while loading.

7. Images without dimensions

Without width and height, the page jumps as images load — the reader loses their line and buttons move. Set both, and reserve space for late content.

8. Redirect chains

http → https → www → trailing slash is three extra round trips. Collapse them into one.

Where to start, ordered by impact

1. Shrink the largest image and convert it to WebP.
2. Delete unused plugins and scripts.
3. Turn caching on.
4. Self-host fonts.
5. Defer non-critical JavaScript.
6. Measure again and compare.

When speed work isn't enough

On some sites individual fixes only go so far: the theme is heavy, plugin dependency runs deep and every update slows things down again. At that point keeping the design and replacing the foundation is a more lasting answer than optimising piece by piece. Preserving URLs and setting redirects where needed reduces the risk of that move — but rankings can still fluctuate for a while, so watch indexing after launch.

Speed isn't a one-off task, it's a habit. Every new page and image should be checked against the same thresholds.