Why is my website slow? Fix a low PageSpeed score
Most slow websites are slow for a few ordinary reasons: images far bigger than they need to be, too many third-party scripts (chat widgets, trackers, embeds), and a heavy slider or video at the top of the page. Test the page in Google PageSpeed Insights, find which of those applies, and fix the biggest one first.
Test the page
- Go to PageSpeed Insights and enter the page's address.
- Read the Mobile tab first. It tests the way a mid-range phone on a slow connection would load the page, which is how Google measures speed.
- Discover what your real users are experiencing shows data from real Chrome visitors, when your site has enough traffic. Diagnose performance issues is a single test run, with the 0–100 score.
The score moves a few points from one run to the next, so don't chase small changes. Test the pages that matter most: the home page, your top landing pages, and pages with a form.
What the numbers mean
Google's Core Web Vitals, with the thresholds for "good":
| Measure | What it means | Good |
|---|---|---|
| Largest Contentful Paint (LCP) | How long until the biggest image or heading near the top appears | 2.5 seconds or less |
| Interaction to Next Paint (INP) | How quickly the page responds to a tap or click | 200 milliseconds or less |
| Cumulative Layout Shift (CLS) | How much the page jumps around while loading | 0.1 or less |
LCP is the one most sites fail. Source: web.dev, Web Vitals.
Fix the common causes
Oversized images. A photo straight off a phone can be 5 MB. Resize images to about 2,500 pixels on the long edge and export them as compressed JPGs before uploading. See Best image size and format for your website.
Third-party scripts. Every chat widget, tracking pixel, review widget, and embedded map adds code from another server, and each one counts against the score, even if it loads late. List what's on the site, and remove the ones nobody uses any more. See Add tracking codes to your site for keeping each tag to one copy.
A heavy first screen. Sliders, background videos, and big animations at the top of the page delay LCP. A single, well-sized photo loads faster than any slider.
Video embeds. Each YouTube player loads about half a megabyte before anyone presses play.
Too many plugins doing the same job. Two SEO plugins or three gallery plugins each load their own files. Deactivate and delete what you don't need.
Slow hosting. If the report's "server response time" is long on every page, the server or its caching is the bottleneck, and that's for your host.
Layout shift. Images without a size, late-loading banners, and cookie notices that push content down raise CLS. Give images and embeds a fixed space.
If your site runs on Dirigible
Dirigible Optimize handles several of these for you:
- Images: uploads are compressed, cleaned of camera and GPS details, and shrunk to 3,000 pixels if they're bigger. Compress older images, on the Images card under Optimize in the admin menu, does the same for images already in your Media Library. See Images and PDFs.
- YouTube: videos show a thumbnail and load the player only when someone presses play. See Click-to-Load YouTube Videos.
- jQuery: the jQuery card defers this script library when every plugin on the page allows it, so it doesn't hold up the first view. See Optimize Settings.
- Daily PageSpeed score: Google tests your home page every day, and the Daily PageSpeed Score card charts 90 days, so you can see whether a change helped. See Daily PageSpeed score.
For the theme's own speed settings, see Speed settings.
If the score stays low after you've dealt with images and extra scripts, the cause is usually in the theme, plugins, or hosting, and that's when it's worth having a developer profile the page.