Check it in five minutes with PageSpeed Insights
Go to PageSpeed Insights, paste in your home page address and run it, then repeat for your most important product page. Select the Mobile tab and read the section at the top headed with real users' experience, not the coloured score lower down.
That top section is field data. Google's documentation for PageSpeed Insights explains that it reports real users' experiences over the previous 28-day collection period, while the lab data below is a simulated load on a single device under fixed network conditions. When a page has too few visits, the tool falls back to data for the whole site, and if the site has too little as well, it shows no field data at all. The lab score is still useful to a developer, but it is not what your buyers saw.
What the numbers should be
Three of the field figures are Core Web Vitals. Google's Web Vitals guidance on web.dev sets the good targets, measured at the 75th percentile of page loads, separately for mobile and desktop. The poor bands come from web.dev's page on each measure, such as the one on Largest Contentful Paint.
| Measure | What it means for a buyer | Good | Poor |
|---|---|---|---|
| Largest Contentful Paint (LCP) | How long before the main banner or heading appears | 2.5 seconds or less | Over 4 seconds |
| Interaction to Next Paint (INP) | How quickly the page responds to a tap, such as opening a menu | 200 milliseconds or less | Over 500 milliseconds |
| Cumulative Layout Shift (CLS) | Whether the page jumps around while loading | 0.1 or less | Over 0.25 |
The 75th percentile means three in four visits must be at least that fast. If LCP on mobile is 4.8 seconds, one buyer in four waited longer than that to see your main banner. What these measures mean for a business site in general is covered in Core Web Vitals for business websites.
Huge banner images are a common cause on factory sites
On a lot of manufacturer websites, the first thing a phone downloads is a full-width photograph of the plant, exported straight from the photographer's camera at several megabytes. That image is usually the largest element on the screen, so the buyer waits for it before the page counts as loaded.
Google's web.dev article on optimising Largest Contentful Paint recommends serving the image at the size it is shown, in a modern format, compressed, and never lazy-loading the main image, because that always adds delay. A banner resized for a phone screen and saved as WebP or AVIF can be a small fraction of the original file.
Sliders, page builders and catalogues add the rest
Sliders. A home page carousel with five plant photographs loads five large images and the script to rotate them, for a visitor who may not stay to see past the first. Replace it with one image and a clear line of text about what you make.
Page builders and heavy themes. Many factory sites are built with drag-and-drop page builders that add a lot of code and scripts to every page. The web.dev LCP article notes that when the main image is added by JavaScript rather than present in the HTML, the browser cannot start loading it until the scripts have run. A slow site that looks fine on the developer's machine is often this. The pattern is explained in why SEO-friendly sites still fail Core Web Vitals.
Catalogues as images. Product ranges shown as a gallery of scanned catalogue pages, each a large image, are slow and also unreadable to search. Specifications belong in HTML text, as set out in what an industrial product page needs before a buyer will enquire.
Plugins and third-party widgets. Chat widgets, social feeds, visitor counters and several analytics tags each add requests. Many sites carry plugins nobody remembers installing.
Slow hosting. If the first response from the server is slow, everything waits. Overloaded shared hosting, or a server far from where most of your buyers are, can be the cause.
Why buyers on phones matter for a B2B site
A purchase engineer may well check a supplier's site on a phone between meetings, at a project site or while travelling, and an overseas buyer may do the same on a roaming connection. A banner that takes several seconds to appear on a mid-range phone on a patchy connection costs you that visit. The other checks overseas buyers make are in what overseas buyers check on an Indian manufacturer's website.
What to ask your developer
Run PageSpeed Insights yourself first, save a screenshot of the mobile field data, then send these questions. A good developer will answer each in plain words.
- What is our mobile LCP, INP and CLS at the 75th percentile in the field data, and which pages fail?
- Which element is the LCP element on the home page and on a product page, and how large is that file?
- Are banner and product images resized for mobile, compressed and served as WebP or AVIF?
- Is the main image lazy-loaded? It should not be.
- Can we replace the home page slider with a single image?
- How much JavaScript does the page builder or theme load on each page, and can unused parts be removed?
- Which plugins and third-party scripts are installed, and which can go?
- What is our server response time, and where is the site hosted?
- Are catalogue pages images, and can the specifications move into HTML text?
- When will we re-check field data? (It reflects 28 days, so allow a month after fixes.)
More pieces on page speed are in the site speed hub, and a further checklist for manufacturers is in EbizIndia's note on manufacturer sites that are slow on mobile.
Questions founders ask
PageSpeed Insights says there is no field data for my site. What does that mean?
It means not enough real Chrome users visited the page, or the whole site, in the last 28 days for Google to report on. You can still use the lab test lower on the page as a guide, but treat its score as a simulation on one device, not a measure of what buyers experience.
My developer says the site is fast because it opens quickly on his computer. Is that enough?
No. A new desktop on office broadband is the best case. Check the mobile field data in PageSpeed Insights, which reflects real users' phones and networks, and ask for the 75th percentile figures for Largest Contentful Paint, Interaction to Next Paint and Cumulative Layout Shift.
Will a faster website bring more enquiries on its own?
Speed removes a reason to leave, but it does not give a buyer a reason to enquire. A fast page still needs clear products, specifications and a quote route. Fix speed alongside those, not instead of them.
Do I need to rebuild the site to make it fast?
Not always. Compressing and resizing images, removing a slider and cutting unused plugins often fixes a large part of the problem on an existing site. A rebuild becomes the better choice when the page builder or theme itself is the main cause.