Why is your website slow? The 5 most common causes
A slow site loses visitors and search rankings. Most speed problems come from a few familiar places, and fixing them starts with measuring.
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When a page takes more than a few seconds to load, many visitors leave before it appears. Google also takes page experience into account when ranking. The good news: most speed problems come from a few familiar places, and you can find them by measuring.
1. Not measuring first
Start with numbers, not guesses. Google PageSpeed Insights or Lighthouse shows three values:
- LCP: When the largest element on the page appears. Aim for under 2.5 seconds.
- INP: How quickly the page responds to a click. Aim for under 200 milliseconds.
- CLS: How much content shifts while the page loads. Aim for under 0.1.
Take the same measurement before and after every change.
2. Oversized images
The cause we see most: images uploaded straight from a phone or camera, several megabytes each. Resize images to their display size and convert them to WebP or AVIF. This alone often makes a big difference.
3. Too many plugins
Each plugin can add its own scripts and styles to the page. Delete the ones you don't use. If two plugins do the same job, keep one. Page builders and sliders are usually the heaviest.
4. Underpowered hosting
Cheap shared hosting becomes the first bottleneck when traffic grows. If the server response time, TTFB, is always high, code improvements only go so far. Sometimes the fastest fix is a better server.
5. No caching or CDN
Caching pages and serving files through a CDN means visitors get a response from the nearest location. After turning on caching, always test dynamic pages such as forms and the cart again.
Where to start
Measure, fix the biggest problem, measure again. Go step by step rather than changing everything at once. That way you see what actually worked.
Frequently asked questions
Does the Lighthouse score need to be 100?
No. The score is a tool, not the goal. What matters is the experience of real visitors. Still, anything above 90 is a good sign.
Can I fix speed issues myself?
Resizing images and removing unused plugins are easy steps. For server, caching or theme issues, our technical support service finds the cause and fixes it.