Why your website is slow (and what it is costing you)
3 June 2026 By Stewart
Someone taps your link on their phone. The screen goes white. They count. One, two, three. By four they have hit the back button and clicked your competitor instead. You will never know they were there.
This is the bit of web performance that gets ignored because it does not show up in any report you read. Bounces are silent. Nobody emails you to say your site was too slow to load while they were standing on a train platform. They just go somewhere else.
According to Think with Google, 53% of mobile users abandon a site that takes longer than three seconds to load. The probability of a bounce goes up by 32% when load time slides from one second to three. Akamai’s research puts conversions down by 7% for every additional second of delay. These are not abstract numbers. They are the difference between a quiet inbox and a busy one.
So why is your site slow? In almost every case I have looked at, it comes down to the same handful of things.
The usual suspects
Images nobody resized. This is the single biggest cause of slow small business websites. Someone uploads a 4MB photo straight from their phone, the page builder displays it at 600 pixels wide, and the browser still has to download the full 4MB before it can show anything. Multiply that by a hero image, a few gallery photos, and some logos in the footer, and you have a page weighing 20MB that should be under 1MB.
Page builders doing too much. Elementor and Divi build sites that real people can edit, which is the upside. The downside is they ship a lot of CSS and JavaScript whether your page uses it or not. Recent testing by WP Rocket put a comparable Elementor site at 75 out of 100 on mobile Lighthouse and a Divi site at 64. A properly built site using the same content sits in the 90s. That gap is not theoretical. It is felt every time someone loads the page on a mid-range Android phone with two bars of signal.
Hosting that costs £3 a month. Shared hosting is fine for a blog nobody reads. For a business that needs to convert visitors into enquiries, it is false economy. Cheap shared servers are slow to respond, slow to serve files, and often based in a different country to your customers. Server response time is the very first thing that happens when someone loads your page. If it takes a second before any content even starts arriving, you have already burned a third of your budget.
Fonts. Lots of fonts. A surprising number of sites load four or five different Google Fonts with multiple weights each. Each one is a separate file the browser has to fetch before it can render text properly. Two fonts are plenty. One is fine.
Third-party scripts. Analytics, chat widgets, review badges, cookie banners, heat maps, Facebook pixels, retargeting tags. Each one adds weight and blocks the browser from getting on with displaying the page. Most small business sites have at least three of these running, often duplicates of the same tool installed twice because nobody removed the old one.
What Lighthouse is telling you
Lighthouse is the free tool built into Chrome that gives your site a score out of 100. You can run it from any page by right-clicking, choosing Inspect, then opening the Lighthouse tab. Google’s PageSpeed Insights runs the same tests and adds real-world data from Chrome users.
The scoring system is simple enough to read.
- 90 to 100 is green and means the site is fast.
- 50 to 89 is amber and means there is real work to do.
- Below 50 is red and means the page is genuinely slow.
The mobile score is the one that matters. Google indexes the mobile version of your site, so a glowing 95 on desktop and a sickly 42 on mobile means you have a slow site in Google’s eyes. A site that scores 95 on desktop but 42 on mobile is still a slow site. Always check the mobile tab first.
Two metrics inside the Lighthouse report do most of the heavy lifting. Largest Contentful Paint (LCP) measures how long it takes for the main bit of content, usually your hero image or headline, to appear. Aim for under 2.5 seconds on mobile. Cumulative Layout Shift (CLS) measures how much the page jumps around as it loads. You know the experience: you go to tap a button and an ad slides in and you tap something else by accident. Anything above 0.1 is too much.
You do not need to fix everything Lighthouse flags. Some recommendations are about edge cases and shave milliseconds. The big wins are almost always images, hosting, and third-party scripts, in that order.
Mobile is the score that matters. Desktop scores are usually 15 to 25 points higher and do not reflect what most of your customers see.
Fix the images first
If you do one thing this week, fix your images. It is the cheapest, fastest improvement available to most small business sites, and it does not require touching any code if your site is on a decent platform.
A bloated image tag looks like this:
<img src="hero.jpg" alt="Our team">That single line loads one file. If the file is 4MB and the user is on mobile, they download all 4MB regardless of how the image is being displayed. The browser cannot start rendering anything else until it has the full file.
A properly optimised image tag looks like this:
<img
src="hero-800.webp"
srcset="hero-400.webp 400w,
hero-800.webp 800w,
hero-1200.webp 1200w"
sizes="(max-width: 768px) 100vw, 800px"
alt="Our team"
loading="lazy"
width="800"
height="500">There is more going on, but it is not complicated. WebP is a modern image format that is roughly 30% smaller than JPEG at the same quality. The srcset tells the browser there are three different sizes available so it can pick the right one for the device. The sizes tells it how big the image will be displayed. The loading="lazy" tells it not to bother downloading the image until the user scrolls near it. The width and height stop the page jumping around as the image loads.
Same image, same content, same business. In real numbers, a hero image that was 3.8MB as a JPEG drops to around 280KB as a properly sized WebP. That is more than ten times smaller. On a 4G connection, that is the difference between two seconds and a tenth of a second.
If your site is on Shopify or a modern platform like Astro or Next.js, most of this happens automatically when you upload an image. If your site is on WordPress, you can install a plugin like ShortPixel or Imagify and it will do the conversion in the background. If your site is on Wix or Squarespace, the platform handles the WebP conversion for you, though the loading and sizing controls are limited.
The fonts and third-party script fixes are similar in spirit. Audit what you need. Remove what you do not. Defer what can wait.
Speed is one of the few things on a website where the fix is mostly known and mostly free. Fix the images, sort the hosting, audit the scripts. Most small businesses are leaving money on the table for the cost of an afternoon’s work and a slightly better hosting plan. You will notice the difference in your enquiries before you notice it in the Lighthouse score.