Website speed: why it matters and how to fix it

Why speed matters more than most business owners realise

The relationship between page speed and user behaviour is well-documented and stark. Studies consistently show that as page load time increases from one second to three seconds, the probability of a visitor leaving before the page loads increases by over 30%. By five seconds, that probability has more than doubled.

For a business website, this isn't an abstract metric. It means a meaningful percentage of the people who clicked on your site in search results never actually saw it — they gave up while it was loading and went to a competitor instead.

On top of that, Google officially uses page speed as a ranking signal through its Core Web Vitals metrics. Poor scores directly suppress your search rankings.

Understanding the numbers

When you run a speed test using Google's PageSpeed Insights (pagespeed.web.dev), you'll see a score from 0 to 100 and a set of specific metrics.

The overall score

• →90–100: Fast. Your site loads well for most users under most conditions.
• →50–89: Needs improvement. There are specific issues worth addressing.
• →0–49: Poor. Your site is actively losing visitors and ranking lower as a direct result.

Always check the mobile score first — Google uses the mobile version of your site for ranking purposes.

Largest Contentful Paint (LCP)

LCP measures how long it takes for the largest visible element on the page to load. Google's target is under 2.5 seconds. The most common causes of a poor LCP are large unoptimised images and slow server response times.

Total Blocking Time (TBT)

TBT measures how long the browser is unable to respond to clicks or scrolls while loading JavaScript. The most common cause is too many third-party scripts — analytics tools, chat widgets, marketing trackers — loading simultaneously.

Cumulative Layout Shift (CLS)

CLS measures how much the page layout jumps around while loading. Target: below 0.1. The most common causes are images without defined dimensions and fonts that swap as they load.

What actually causes slow websites

Unoptimised images

Images are by far the most common cause of slow load times. A photo from a modern phone is typically 3–10MB. Displayed on a website, that same image only needs to be 100–300KB to look sharp. Use tools like Squoosh or TinyPNG to compress images before uploading, and use WebP format where possible.

Too many third-party scripts

Every tool added to your website — analytics, live chat, marketing automation, cookie consent — adds a script that must load before the site is fully interactive. Audit which tools you actively use and remove everything else.

Slow hosting

Time to First Byte (TTFB) — how quickly the server starts sending data — is determined by your hosting. Cheap shared hosting typically results in slow TTFB. If your server response time is consistently above 600ms, upgrading your hosting or moving to a platform with a global CDN will have an immediate impact.

The fixes that make the biggest difference

• 1.
  Compress and resize your images.

  Use Squoosh (squoosh.app) to compress images for free, targeting under 200KB per image.

• 2.
  Remove unused third-party scripts.

  Remove anything you installed and forgot about. One fewer tracking script can noticeably reduce TBT.

• 3.
  Enable lazy loading for images.

  Images load only when about to come into view rather than all at once. Most modern CMS platforms support this as a built-in option.

• 4.
  Consider your hosting.

  If server response time is the problem, upgrading to a host with built-in CDN support will have more lasting impact than any front-end fix.

• 5.
  Set explicit dimensions on images.

  Adding width and height attributes to every image prevents layout shift (CLS) as the page loads.