What makes a web page slow, and how to check yours

Scripts are the usual suspect

Every analytics tag, chat widget, social button and tracking pixel is a script. Each one is a separate download, and many of them run before your page can draw. A site with six of them is waiting on six strangers' servers before it shows a headline.

Look at what you actually use. A chat widget nobody answers is weight for nothing. A second analytics tool that duplicates the first is weight for nothing. Remove what you do not read.

Images bigger than the screen

A photo straight from a phone is far larger than any screen it will be shown on. Upload it as-is and every visitor downloads the whole thing, then the browser shrinks it. Resize images to the size they display at, save them in a modern format, and set width and height so the layout does not jump when they arrive.

Hero images deserve the most care because they load first and sit at the top. One good, properly sized hero image beats a carousel of five.

Fonts and video

Each custom font weight is a file. Regular, bold, italic and bold italic in two families is eight downloads before your text can settle. Pick one family and two weights, and let the system font stand in while they load.

Autoplaying video is the heaviest thing you can put on a page. It starts downloading whether the visitor wanted it or not, and on a phone it competes with everything else. The fix is click-to-load: show a still frame and fetch the video only when someone presses play.

What the builder ships

Website Builder Studio counts page views and conversions on the server. No analytics script and no cookie is added to your site unless you add your own. If you add a Google Analytics 4 measurement ID, the tag loads only after a visitor accepts cookies on sites that show a banner.

A hero video is click-to-load: give the in-app assistant a YouTube or Vimeo link and nothing downloads until a visitor presses play. A booking link from Calendly, Cal.com, Acuity or the others adds a book-a-time section that loads only when a visitor opens it. Both stay out of the way until they are wanted.

Every page also passes a check that runs before anything publishes, validated against Google Search Essentials and modern web standards. What the check cannot do is stop you adding a heavy widget of your own later, so the two sections below are still worth knowing.

How to check with your own browser

Open the page, open developer tools, and pick the Network tab. Reload. You get a list of every file the page fetched, its size and how long it took. Sort by size. The biggest rows are your first fixes.

The Performance tab records a load and shows what the browser was doing each moment. You do not need to read all of it. Look for long bars before the first paint; those are the things blocking your page from appearing.

• Network tab, sorted by size, shows what to shrink or drop.
• Disable cache before reloading so you see a first visit, not a repeat.
• Throttle to a slow connection to see what a phone on a weak signal sees.

How to check with PageSpeed Insights

Google's PageSpeed Insights is a page you paste an address into. It loads your page from a data center and reports what it measured, and if enough real visitors have loaded your site it shows what they experienced too.

Read the diagnostics, not the score. The score changes between runs and between devices. The diagnostics name the exact file, image or script that cost the most, and that is the list you act on.

Check the mobile result first. Google reads the mobile version of your site, and a phone on a cellular connection is the hardest case your page will meet.