How to run a website speed test, and what the result means

How heavy business homepages are

Weight is what a phone has to download before it can show the page. Half the homepages we weighed came in under 179 KB. One in ten came in at 667 KB or more, nearly four times the median, and in some trades the heavy end sits a long way further out:

• Aesthetic, 33 sites: median 260 KB, heaviest tenth from 1012 KB.
• Professional services, 55 sites: median 163 KB, heaviest tenth from 888 KB.
• Auto and marine, 35 sites: median 184 KB, heaviest tenth from 800 KB.
• Seniors and mobility, 43 sites: median 220 KB, heaviest tenth from 776 KB.
• Home improvement, 25 sites: median 272 KB, the heaviest of any group, and heaviest tenth from 667 KB.
• Trades and home services, 111 sites: median 187 KB, heaviest tenth from 633 KB.
• Urgent services, 51 sites: median 158 KB, heaviest tenth from 508 KB.
• Clinics, 65 sites: median 156 KB, heaviest tenth from 397 KB.

In professional services, the heaviest tenth start at more than five times the weight of a typical homepage in the same group. A heavy page is more to fetch on one bar of signal, so if yours might be in that tenth, a speed test is the way to find out whether it costs you any time. The rest of the study, trade by trade, is in what we found in 467 business websites.

How to run a website speed test with Google PageSpeed Insights

You need the address of the page and a minute. Nothing to install and nothing to pay.

1. Open PageSpeed Insights, Google’s own free speed checker.
2. Paste in your homepage address and start the test.
3. When it finishes, make sure you are reading the mobile result. That is the phone your customer is holding.
4. Run it again. Timings on a slowed connection vary from one run to the next, which is why our own gate takes the middle of three.
5. Repeat for the page your Google listing or your ads send people to, if that is not the homepage.

The test runs from Google’s end, so your own internet connection does not change the result. That makes it a fairer website loading speed check than opening the site on your own phone and counting.

Reading a Google PageSpeed result in plain English

The big number at the top is a score out of 100. It is Google’s summary of the whole test, handy for comparing this month with last month. Read the timings before you read the score.

The timing to find first is Largest Contentful Paint. It means: when did the main thing on the screen appear? Usually that is your headline or your main photograph. Until it appears, the visitor is looking at a page that has not really started. Droom builds every page so it appears within 2.5 seconds on a slowed phone connection.

Two more are worth knowing by name. First Contentful Paint is when anything at all appears, even a logo or a background colour. Cumulative Layout Shift is how much the page jumps around while it loads, the thing that makes someone tap the wrong button because the text moved under their thumb.

Below the figures sits a long list of suggestions. That part is written for whoever builds your site, so you do not need to understand it. Copy the address of the report and send it to them.

Website speed and page weight are different measurements

A light page can still be slow, and a heavy one can be quick. We measured both cases while setting up our own speed gate, on a slowed 4G connection. A 2.9 MB page that had its headline written into the page itself, and loaded the heavy part afterwards, showed its main content in 212 milliseconds. A 302 KB page that made the browser run a script before showing anything took 3008 milliseconds.

The second page was a tenth of the weight and fourteen times slower. The order things load in decides most of it. A homepage on the heavy list above is a reason to run the test, and the test is what tells you whether the weight is costing you anything.

What Droom builds to

Every Droom website is timed by a script before it goes anywhere near a customer. It opens each page on a phone-sized screen, 390 pixels wide, over a connection set to ordinary 4G as Lighthouse defines it (Lighthouse is the engine PageSpeed Insights runs on), with the processor slowed four times to roughly what a mid-range Android phone manages. It loads every page three times and takes the middle result.

If Largest Contentful Paint comes in over 2.5 seconds on any page, the build fails and gets fixed. Weight is reported alongside and never gated, for the reason in the section above. The script ships inside every client site’s own files, so a page you pay for is held to it from the start. How the rest of a build is put together is on the websites page, and the screen-size side of the same testing is in the 14 widths every build is tested at.

When the speed test says your site is slow

When a page fails our own speed gate, the script prints the usual fixes in order. In plain English, they are for these, so send your report to whoever maintains the site and ask which applies:

• The headline or main photograph waits for a script to run before it is allowed to appear.
• Everything further down the page loads at once, before the visitor has scrolled to any of it.
• The fonts arrive late and hold back the text.

Each one is a change to how the existing page loads, so ask for a price on that fix before anyone prices you a new site. If the same pages also look wrong on a phone, this guide to mobile faults explains the two usual causes.

If nobody maintains the site any more, or you would rather someone else read the report, send it to me. The free Field Test checks your site the way a customer uses it, on a real phone, and comes back with what fails on video and a fixed price to fix it.