Nobody decides to build a slow website. They accumulate. A plugin here, an uncompressed photo there, a chat widget somebody asked for in 2023 and never used. Then one day the site takes six seconds to appear and the enquiries have quietly halved.
The causes are boringly consistent. Here they are, in roughly the order we find them.
Check yours first, in two minutes
Before reading further, get a number. Open PageSpeed Insights, paste your address and look at the mobile score, not the desktop one. Desktop flatters everybody.
Three figures matter more than the headline score:
- Largest Contentful Paint — when the main thing on screen finishes loading. Aim under 2.5 seconds.
- Interaction to Next Paint — how long before the page responds when tapped. Aim under 200 milliseconds.
- Cumulative Layout Shift — how much the page jumps around while loading. Aim under 0.1.
If the mobile number is above four seconds, the rest of this article is about you.
The five usual causes
1 · Images straight from a camera
The most common and the easiest to fix. A photo from a modern phone is often four megabytes and five thousand pixels wide, displayed in a box eight hundred pixels across. The visitor downloads all of it. Resize to the size actually displayed, save as WebP, and a page can get three times faster in an afternoon with no other change.
2 · Page builders
Drag-and-drop editors are wonderful for the person building and expensive for the person visiting. Producing a three-column layout can ship hundreds of kilobytes of code that a dozen lines of CSS would have handled. You rarely notice on the fast laptop you built it on.
3 · Plugin sprawl
Each plugin loads its own scripts and styles, usually on every page whether that page needs them or not. A contact form plugin loading on your blog posts, a slider loading where there is no slider. Twenty plugins is twenty sets of files before your content appears.
4 · Third-party scripts
Analytics, heatmaps, chat widgets, advertising pixels, fonts from several providers, a cookie banner, an embedded video player. Every one is a connection to another company’s server, and your page waits for servers you do not control. This is also the category nobody audits, because each one was added by a different person for a reason that seemed small.
5 · Cheap shared hosting
If the server takes 1.5 seconds to send the first byte, nothing you do in the browser recovers it. Shared hosting at three euro a month is shared with hundreds of other sites, and you inherit their busy periods.
What the delay actually costs
The industry research on this is consistent enough to plan around: every extra second of load time measurably reduces the share of visitors who stay and act, and mobile users abandon fastest of all. Rather than quoting someone else’s percentage at you, do the arithmetic on your own numbers.
If a thousand people a month reach your site and a tenth of them leave because it is slow, that is a hundred people. What is one customer worth to you, and how many of that hundred would have become one?
Then there is the compounding part. Google uses these measurements as a ranking input, so a slow site gets fewer visitors and converts fewer of the ones it gets. The two losses multiply rather than add.
What to do about it, in order
- Fix the images. Highest return, lowest risk, often a single afternoon.
- Remove what you do not use. Every plugin and script nobody can justify. Be ruthless; you can always put one back.
- Audit the third parties. For each one ask who looks at this data and when they last did. Most fail that question.
- Move to better hosting. Cheaper than it sounds and fixes the floor you cannot otherwise get under.
- Then consider the platform. If the site is still slow after the first four, the platform itself is the limit, and more optimisation is throwing good money after bad.
That last point is the uncomfortable one, so we will be direct about our own interest: we build websites, so “you need a new site” is a conclusion we profit from. Which is exactly why we put it fifth, after four things you can do yourself for nothing.
How fast is reasonable?
A content site has no excuse for a first paint over one second on a decent connection. We hold ourselves to it: the proof section of our home page measures this page in your own browser as you read, and shows the number whatever it says.
If you want this handled rather than attempted, it is part of every website build and the first thing we look at in any SEO engagement.
Written by the people who would also do your work. If any of this applies to you, tell us what you are dealing with — the first look is free and you keep the findings.