A slow website is one of the few problems in your business that never shows up on a report. Nobody emails to say they gave up waiting.
You see the symptoms instead. Enquiry numbers that look thin next to your visitor numbers. A competitor you privately think is worse at the work, getting asked to quote for jobs you never hear about.
The usual reaction is to buy more traffic. That is the expensive way round, because if the page loses people before it appears, more visitors just means more waste.
So here is the honest version: what the UK evidence says, what Google publishes as the standard, and how to tell whether this is costing you.
TL;DR: Google documents 2.5 seconds as the target for a page’s main content to appear, measured at the 75th percentile of real visits, and states that Core Web Vitals are used by its ranking systems. Ofcom’s Mobile Matters report puts 70.7% of UK mobile connection attempts on 4G rather than 5G, found 28% of 4G connections delivered under 10 Mbit/s, and measured a 10MB download taking 2.0 to 3.2 seconds to arrive. Ofcom also reports 20% of UK online adults use a smartphone as their only route online, so if your site is heavy, a fifth of your market meets it at its worst.
What a slow website actually costs you
Speed gets treated as a technical score. It is a commercial leak, and it shows up in three places: enquiries you never receive, advertising you pay for twice because the click is charged whether or not the page loads, and position in search results.
Put your own numbers against it. Say your site gets 1,200 visits a month, two in every hundred enquire, and you win one enquiry in four at an average job value of £4,000. That is 24 enquiries and roughly £24,000 of work a month.
Now assume a slow website loses a tenth of your mobile visitors before anything renders. That is two or three enquiries a month, and £8,000 to £12,000 of work a quarter. Most owners would fight hard for that in a price negotiation and never look for it here. If you do not know what one enquiry costs you, start with our guide to what a lead should actually cost.
Your buyer is not sitting in an office on fibre
This is where owners get a false reading. You check your site from your desk, on good broadband, with the images already stored. It is quick. Of course it is. Ofcom’s Mobile Matters report, which measures real connections on UK smartphones rather than lab conditions, found 70.7% of mobile connection attempts went to 4G rather than 5G, and 28% of 4G connections delivered less than 10 Mbit/s. On 4G it measured a 10MB download taking 2.0 to 3.2 seconds, before a browser draws anything.
Ofcom’s Adults’ Media Use and Attitudes report, published in April 2026, adds the other half: 20% of online adults in the UK rely on a smartphone as their only way of getting online, up from around 12% in 2019. One in five of your potential customers has no laptop to fall back on.
So picture a site manager on a trading estate near Fareham, two bars of signal, next to a machine that has stopped, looking for someone who can come out this week. You are judged in those seconds against two other firms.
The standard Google publishes, in plain terms
You do not have to guess what good looks like. In its Search Central documentation, Google sets the target for Largest Contentful Paint, the moment the main thing on the page becomes visible, at 2.5 seconds or less. It is assessed at the 75th percentile of real visits, so three quarters of visitors must get there inside 2.5 seconds, not only the lucky ones. Google also states that Core Web Vitals are used by its ranking systems.
Google also says, though, that good scores do not guarantee top rankings. Taking a site from awful to solid is worth money. Taking it from solid to immaculate is not.
How to tell if you have a slow website in five minutes
No agency required, and no cost. Do this before anyone quotes you.
- Take your phone off wifi so you are on mobile data, like most of your buyers.
- Open a private browsing window, so you are not served a stored copy.
- Load your homepage and main service page, counting the seconds until you can read something useful.
- Do the same for two competitors you lose work to.
- Run both pages through Google’s free PageSpeed Insights tool and read the real-world mobile section, not the laboratory score underneath.
Past four or five seconds, you have a slow website and it is costing you enquiries. Inside two and a half, this is not your problem.
What usually makes a business website slow
The cause is almost never exotic. It is one of four everyday things.
- Photographs loaded straight off a camera. One 6MB site photo can weigh more than an entire well built page.
- A video playing silently behind your homepage headline, which looked impressive at sign off and costs every mobile visitor.
- Plugins added for one job years ago and never removed, each loading code on every page.
- Cheap shared hosting, where your site queues behind hundreds of others on one machine. None of this is a reason to rebuild, only to ask for a tidy up.
What it costs to fix, and when it is not worth the money
For most owner managed UK businesses, a focused speed job runs from a few hundred to a couple of thousand pounds. Compressing images, removing dead plugins, cleaning up scripts and moving to proper hosting covers most cases, at a fraction of a rebuild. Our breakdown of what a website should cost in the UK is a sense check if anyone suggests a new one.
There are cases where you should not spend a penny. If your work comes almost entirely from referrals, or your pages already load inside two and a half seconds, speed is not your constraint, and anyone selling a performance package is selling a number rather than an outcome. Be wary of a rebuild sold on the back of a poor score too, because a slow website is usually a maintenance failure, not a design failure.
Three questions to put to whoever looks after your site
- What is our Largest Contentful Paint on mobile, on real visits? A good answer is a number in seconds.
- How heavy is our homepage in megabytes, and what is the biggest thing on it?
- What would you fix first, what will it cost, and what should it change?
Anyone answering the last one with tasks rather than an outcome is not thinking about your business. Speed is the floor, not the building, so if the site is already quick, work through why a website gets visitors but no enquiries next.
How fast should my website load?
Google documents 2.5 seconds or less for Largest Contentful Paint, the point at which the main content of a page becomes visible. It is measured at the 75th percentile of real visits, so three quarters of visitors need to reach that mark, not just those on fast connections. As an owner’s test, if you cannot read something useful on your homepage within two and a half seconds on mobile data, it is too slow to win work.
Does a slow website affect my Google rankings?
Yes, but less than people selling speed services imply. Google states in its Search Central documentation that Core Web Vitals, which include loading speed, are used by its ranking systems. Google also says plainly that good scores do not guarantee top rankings, and that chasing a perfect score purely for search reasons may be a poor use of time. The bigger commercial cost of a slow website is not position in search, it is buyers leaving before the page appears at all.
How do I check if my website is slow?
Turn wifi off on your phone so you are on mobile data, open a private browsing window so you are not shown a stored copy, then load your homepage and main service page and count the seconds until something readable appears. Do the same for two competitors. Then run both pages through Google’s free PageSpeed Insights tool and read the real-world mobile data rather than the laboratory score.
Is it worth paying to speed up my website?
It depends on your traffic and where your work comes from. For a UK business with steady search or paid traffic and pages taking four seconds or more on mobile, a focused speed job of a few hundred to a couple of thousand pounds usually pays back quickly in recovered enquiries. If your work comes mainly from referrals, or your site gets only a couple of hundred visits a month, the money is better spent elsewhere.
Speed is one of the few marketing problems with a published standard and a bill you can predict, so it is worth settling rather than wondering about. Do the five minute test first, and if your pages are crawling on mobile data, send the site to Damteq and we will tell you what is slowing it down, what a fix would cost and whether it would bring you more enquiries, including when the answer is that your site is fine and the problem sits elsewhere.
