How to Speed Up a Slow Website
Most speed advice is a list of twenty things to try. The faster route is to find the one or two things that are actually slow on your pages, fix those, and measure again. We learned that the hard way on this site, so this guide starts with measuring.
What Site Audit flags, and where the lines are
| Issue | Flagged when |
|---|---|
| Slow page | It takes over 3 seconds to load |
| Very large page | Its code and content come to over 3 MB |
| Scripts or styles that hold up loading | The browser must download them before it can show anything |
| No compression | The page is sent at full size when it could be squeezed |
| Slow server | Your server takes a long time to start sending the page |
Slow and very large pages are warnings, because they cost you visitors. The other three are notices. They are often the reason a page is slow, so fixing them tends to clear the warning too.
Measure before you change anything
Run the page through Google's free PageSpeed Insights and look at the mobile result first. Under "Diagnose performance issues" it names the biggest files and how long each one held things up. Write the main figures down, because you want a before and an after.
When we built getduality.com, our first move was to host our font ourselves instead of loading it from Google, which plenty of speed guides recommend. On a slowed-down phone test, the home page's main content then appeared after 1.85 seconds, against 1.81 before. Nothing improved, because the font was never the problem.
The real cost was our stylesheet: about 60 KB, sent uncompressed. Turning on compression on the server, in the same change as switching on HTTP/2, shrank it to 14 KB, and the same test dropped to 1.24 seconds. Compression still does most of the work: today the stylesheet is 68 KB as written and about 16 KB as sent.
The usual suspects on a small business site
Your biggest problem may be different from ours. These are the common ones, roughly in the order they tend to matter.
Images straight from a phone or camera
A single photo can be 4 or 5 MB. Resize each image to the width it's actually shown at, compress it, and use WebP where your platform supports it. On WordPress, plugins such as ShortPixel, Smush or Imagify do this automatically; elsewhere, the free Squoosh app works well. Shopify, Wix and Squarespace resize and convert for you, but only if you upload a sensible file to begin with.
No caching
Without caching, your server builds every page from scratch for every visitor. That's the usual cause of the "slow server" notice. Many hosts include caching; on WordPress, WP Rocket, LiteSpeed Cache or W3 Total Cache add it.
No compression
Gzip or Brotli shrinks text files before they're sent, as our stylesheet showed. It's often one switch in a hosting panel, a caching plugin or a service such as Cloudflare. Hosted builders do it already.
Things you added once and forgot
Every plugin, app, chat widget, font and tracking script adds weight. On our own home page, the single largest download is Google's analytics script, about 175 KB of a 400 KB first visit. We keep it because we use the figures. Go through yours and ask the same question of each one. On Shopify, uninstalled apps sometimes leave code in the theme, so check with the app's support.
Scripts that hold up loading
Chat widgets, social feeds and booking embeds rarely need to load before your text. Speed plugins have a "defer JavaScript" or "delay JavaScript" switch. Test the site afterwards, because it occasionally breaks a feature.
One enormous page
A page over 3 MB usually has something pasted in that shouldn't be there: a huge embedded image, a page builder section repeated many times, or a very long list. Split it or trim it.
If it's still slow
When caching is on and the pages are light but the server still takes a long time to respond, the hosting plan is often the limit. Cheap shared hosting can struggle with a busy WordPress site. Ask your host what they can offer before you move.
Checking the difference
Run PageSpeed Insights again on the same page and compare it with your notes. Lab scores move a few points between runs, so look for a clear change rather than one or two points.
In Duality, tick the page in Site Audit and choose Verify my fixes to time it again straight away. The desktop and mobile speed scores in your weekly and monthly reports will show whether the change holds.