Why Is My Website Slow? Diagnose It Yourself
By CodexierPublished 6 min read
A slow website is rarely slow for a mysterious reason. Almost every case comes down to one of four things: a server that responds late, images that are far bigger than they need to be, scripts from third parties that block the page, or a theme and plugin stack that ships too much code. The good news is that free tools separate these causes reliably. This guide walks through the diagnosis in order, so you know what you are dealing with before you spend a krona on fixing it.
Measure with free tools
Three free tools cover the whole diagnosis. PageSpeed Insights gives you both real-visitor data and a lab run with a list of opportunities. WebPageTest shows a waterfall of every file the page loads, in order, which is the clearest way to see what is blocking what. Your browser's developer tools, under the Network tab, show the size and timing of each request on your own machine. Test on mobile settings, because that is where most of your visitors from Google are, and test an inner page, since those are often slower than the homepage. The Core Web Vitals guide explains what the three headline numbers mean.
Hosting and server response
Look for the time to first byte, the gap between the request and the first data arriving. If it is consistently over half a second, the page is slow before a single image has been considered. Causes are cheap shared hosting with too many sites per server, a CMS doing heavy database work on every visit with no caching, or a server far from your visitors. For a Swedish audience, hosting in the Nordics or at least in Europe matters. The fixes, in order of cost: enable page caching, add a content delivery network, and finally move to a better host. Moving is disruptive, so exhaust caching first.
| Symptom | Likely cause | First fix |
|---|---|---|
| Time to first byte over half a second on every page | Overloaded shared hosting or no caching | Turn on full-page caching |
| Fast on repeat visits, slow the first time | Cache works, server is slow to build pages | Caching for logged-out visitors, database cleanup |
| Slow only at certain hours | Shared server under load from other sites | Upgrade hosting tier or move |
| Slow from abroad, fine from Sweden | Single server, no CDN | Add a CDN |
Images and fonts
Once the server responds quickly, page weight is the next suspect, and images are nearly always the bulk of it. A photo uploaded straight from a phone camera can be several megabytes, when the space it fills on screen needs a fraction of that. Sort the Network tab by size and look at the top ten files. If they are images, the fix is mechanical: resize to the displayed dimensions, convert to a modern format such as WebP or AVIF, and lazy-load everything below the first screen. Fonts are the smaller cousin of the same problem: each weight and style of a web font is a separate download, and sites often load six when they use two.
- Resize images to the largest size they are actually shown at, not the size the camera produced.
- Convert to WebP or AVIF; most CMS platforms have a plugin or setting that does this on upload.
- Lazy-load images below the fold so they do not compete with the hero image and text.
- Limit web fonts to two weights and let the system font stand in while they load.
- Check hero sliders: five full-width images in a carousel cost five times the download for one visible slide.
Third-party scripts and plugins
The third cause is invisible in a screenshot and obvious in a waterfall: scripts. Every chat widget, analytics tag, heat-map tool, social embed, booking widget and cookie banner adds requests, and many of them block the browser from drawing until they finish. Page builders and multipurpose themes add their own layer, loading sliders, animation libraries and icon sets on every page whether used or not. PageSpeed Insights lists unused JavaScript and third-party usage by origin. Go through the list with one question per entry: who in the company reads the data this produces, or uses this feature? Anything without a name attached gets removed.
What to fix yourself and what to hand over
Several fixes are safe for a non-developer: turning on caching in the hosting panel, installing an image optimisation plugin, removing tags and widgets nobody uses, and deleting inactive plugins. Others are best handed to a developer, because a mistake takes the site down or breaks a form: changing hosts, replacing the theme, rewriting how scripts load, and restructuring the page templates. A performance and SEO optimisation starts from 7,990 kr and covers the developer side end to end; the plans are on our pricing page.
When you do not need this: if PageSpeed Insights shows your real-visitor Core Web Vitals as Good on mobile, your site is fast enough for both Google and people, and further tuning is a hobby rather than an investment. If the site is slow but is about to be rebuilt anyway, put the money into the rebuild's requirements instead of patching the old one. If you have run the tools and cannot tell which of the four causes you have, book a short call and we will read the results with you.
Frequently asked questions
Is my hosting provider to blame?
Only if the time to first byte is slow. Check it in PageSpeed Insights or the Network tab. If the server answers in a few hundred milliseconds, the delay is in what the page loads afterwards, and changing host will not help.
Will a caching plugin fix everything?
It fixes slow page generation, which is one of the four causes. It does nothing for oversized images or blocking scripts, and it can cause stale content if configured carelessly. Turn it on, measure again, then continue down the list.
How fast is fast enough?
Google's thresholds are a good benchmark: main content visible within 2.5 seconds and responses to taps within 200 milliseconds, measured on real mobile visitors. Beyond that, improvements rarely change what visitors do.
Ran the tools and still not sure what you are looking at?
Fifteen minutes with a developer: share your PageSpeed results and we tell you which of the four causes you have, what you can safely fix yourself and what a proper optimisation would cost.
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