A slow website is like a shop assistant who leaves the customer standing at the counter for five minutes. Some people leave before they even see what you offer – and Google knows it, which is why speed is one of its ranking factors. In this article we'll cover how to measure website speed, what kills it most often, and which fixes bring the biggest effect. Ordered practically: from quick wins to jobs that need a specialist.
Why speed matters
Visitors don't forgive. Every extra second of loading means some people give up – especially on mobile with an average connection. For an e-shop, slow loading translates directly into the cart: people who wait don't buy.
Google measures Core Web Vitals. Three metrics Google tracks with real visitors: LCP (how fast the main content appears – target under 2.5 s), INP (how quickly the page responds to clicks – target under 200 ms) and CLS (how much content jumps around while loading – target under 0.1). Sites that hit the limits get an edge in search.
Speed is part of trust. A snappy website feels professional. A slow one quietly says "this is what working with us will feel like".
How to measure it (free, one minute)
- PageSpeed Insights – paste your URL and get mobile and desktop scores including real-user Core Web Vitals (if the site has enough traffic). Measure mobile – that's where problems live and where Google measures.
- Search Console → Core Web Vitals – an overview of which pages pass and which don't.
- Common sense: open your own site on a phone over mobile data. Whatever annoys you annoys your customers.
What slows websites down most (and how to fix it)
1. Images – culprit number one
A phone photo can easily be 5 MB; a page then carries twenty of them. The fix: modern formats (WebP, AVIF) instead of JPG/PNG, dimensions matching the actual display size, and lazy loading (below-the-fold images load only when the reader scrolls to them). Converting images to WebP alone can cut page weight by tens of percent – typically the biggest effect for the least work.
2. Bloated JavaScript and plugins
Every plugin, chat widget, tracking script and slider must download and execute. On WordPress it's common to find 30+ plugins with half of them unused. The rule: whatever the site doesn't actively need goes away. For analytics, one properly configured script is enough.
3. Cheap hosting
Bargain hosting means a shared server carrying hundreds of sites that chokes at peak times. Before tuning milliseconds elsewhere, check the server response time (TTFB in PageSpeed) – if the server takes longer than ~0.8 s to respond, the foundation everything stands on is what's slowing you down.
4. Web fonts and third-party scripts
Every font and every third-party script (maps, videos, widgets) is more waiting. Limit fonts to 1–2 families with only the weights you need; embed videos as a click-to-play thumbnail instead of auto-loading the player.
5. Missing cache and CDN
Cache means the page doesn't have to be rebuilt on every visit; a CDN serves it from a server near the visitor. On modern platforms both are a given; on older sites, a common gap.
When tuning isn't enough and it's time to rebuild
When a site stands on an outdated template, ten years of plugins and cheap hosting, optimization is like tuning a Trabant. The tell-tale signs: mobile score under 40, LCP over 4 seconds even after image optimization, and every change breaking something. At that point it's usually cheaper to rebuild on a fast foundation – why I use React and Next.js for that is covered in why Next.js for a business website.
Summary
You can measure your website speed for free with PageSpeed Insights; the goal is green Core Web Vitals (LCP under 2.5 s, INP under 200 ms, CLS under 0.1). Biggest effect for the least work: images in WebP with proper dimensions and lazy loading, a plugin and script clean-up, decent hosting, cache + CDN. If even that doesn't help, it's time to think about a new foundation.
Don't want to deal with it yourself? Speed monitoring is part of my website care service – measurement, optimization and regular maintenance. And if your site is on fire right now, there's express help.