Your website looks great, your content is compelling and your digital marketing campaigns are bringing in visitors. But what happens when your website takes too long to load?

Website performance is often one of the most overlooked aspects of digital marketing. Businesses invest in attractive designs, engaging content and paid advertising, yet fail to address the technical issues that influence how quickly visitors can access and interact with their websites.

A slow website can frustrate potential customers, interrupt the user journey and undermine conversion opportunities.

Fortunately, Google’s PageSpeed Insights provides a free and accessible way to identify performance problems and understand where improvements may be needed.

But interpreting the results isn’t always straightforward.

Here’s how to use PageSpeed Insights effectively, understand what the numbers mean and identify potential causes of poor website performance.

What Is Google PageSpeed Insights?

Google PageSpeed Insights (PSI) is a free diagnostic tool that analyses the performance of individual web pages on mobile and desktop devices.

It evaluates loading behaviour, responsiveness and visual stability, providing performance metrics and recommendations for improvement.

You can access the tool at:

https://pagespeed.web.dev/

Simply enter a website URL, click Analyse and review the results.

The report contains two important types of information.

Real-user data (Field Data)

This information is collected from eligible Chrome users over a rolling 28-day period. It reflects how actual visitors experience your website across different devices and network conditions.

Not every website has sufficient data available, particularly newer or lower-traffic websites.

Simulated performance data (Lab Data)

PageSpeed Insights also uses Google’s Lighthouse testing technology to simulate how a web page loads under controlled conditions.

This information is particularly useful for identifying technical problems and testing potential improvements.

Understanding the distinction is important. A page may perform well in a simulated test while some real users continue to experience performance problems.

Understanding Your PageSpeed Insights Score

After running a test, PageSpeed Insights provides a performance score out of 100.

The results are grouped into three categories:

• 90–100: Good performance.
• 50–89: Needs improvement.
• 0–49: Poor performance.

While these scores provide a useful indication of performance, they should not be treated as the only measure of website quality.

A score of 100 doesn’t automatically mean a website provides an excellent user experience, just as a lower score doesn’t necessarily mean a website is unusable.

The score is generated from a simulated test and can fluctuate between runs.

The real objective is not simply to achieve a perfect score. It’s to deliver a fast, stable and responsive website for your visitors.

Understanding Core Web Vitals

Google’s Core Web Vitals are three key measurements used to evaluate important aspects of the website experience.

1. Largest Contentful Paint (LCP): How Quickly Does Your Page Load?

Largest Contentful Paint measures how long it takes for the largest visible content element to render on screen.

This might be a prominent image, a heading or another substantial content element.

Google’s recommended LCP threshold is 2.5 seconds or less.

When LCP is slow, visitors may spend several seconds looking at an incomplete page before the main content becomes visible.

Common causes include:

• Oversized images.
• Slow server response times.
• Render-blocking CSS or JavaScript.
• Poor caching configurations.
• Large hero banners or background images.

What to investigate: Identify which element is responsible for LCP and determine whether its loading is being delayed by images, scripts, stylesheets or server performance.

2. Interaction to Next Paint (INP): How Responsive Is Your Website?

Interaction to Next Paint measures how quickly a website responds visually to user interactions such as clicks, taps and keyboard input.

Google considers an INP of 200 milliseconds or less to be good.

A poor INP score might indicate that visitors experience delays when opening menus, selecting options or interacting with forms.

Common causes include:

• Excessive JavaScript execution.
• Resource-intensive third-party scripts.
• Complex interactive elements.
• Long tasks blocking the browser’s main thread.

What to investigate: Review the JavaScript resources and interactive functionality on your website. Identify whether unnecessary scripts or poorly optimised functionality are delaying interactions.

3. Cumulative Layout Shift (CLS): Does Your Page Move Around While Loading?

Cumulative Layout Shift measures unexpected movement of visible page elements.

Have you ever tried to click a button, only for the page to shift and move the button elsewhere?

That’s an example of poor visual stability.

Google recommends a CLS score of 0.1 or less.

Common causes include:

• Images without defined dimensions.
• Advertisements or embedded content loading unexpectedly.
• Fonts that cause text to resize.
• Dynamically inserted website elements.

What to investigate: Identify which elements are shifting and ensure that appropriate space is reserved before images, advertisements and other dynamic content load.

How to Troubleshoot a Slow Website Using PageSpeed Insights

Once you’ve reviewed the main performance indicators, the next step is identifying what is causing the problems.

Step 1: Test Both Mobile and Desktop Performance

A website may perform well on a desktop computer but struggle on mobile devices.

Mobile testing is particularly important because visitors may be using slower networks, less powerful devices or browsers with limited processing resources.

Run tests for both device categories and compare the results.

Pay particular attention to differences in loading speed and responsiveness.

Step 2: Review the Performance Diagnostics

Scroll to the Lighthouse diagnostics section of your PageSpeed Insights report.

Depending on the detected issues, you may see recommendations relating to image delivery, caching, JavaScript execution, network requests and rendering performance.

These findings help identify potential bottlenecks.

However, not every recommendation will have the same impact.

Prioritise issues affecting the largest visible content, loading delays and responsiveness rather than attempting to resolve every warning simultaneously.

Step 3: Investigate Images

Unoptimised images are a common cause of slow-loading websites.

High-resolution photography, large background images and oversized graphics can introduce unnecessary download requirements.

For WordPress websites, consider:

• Compressing images before uploading them.
• Using modern image formats such as WebP or AVIF where appropriate.
• Serving images at suitable dimensions.
• Implementing responsive images.
• Lazy-loading images located below the initial visible area.

Be careful not to lazy-load the main image responsible for Largest Contentful Paint, as this can delay its appearance.

Step 4: Examine JavaScript and CSS

Modern WordPress websites frequently rely on multiple plugins, themes, page builders and third-party integrations.

Each may introduce additional stylesheets or JavaScript files.

These resources can increase download requirements, delay rendering or create unnecessary work for the browser.

PageSpeed Insights can help identify scripts and stylesheets contributing to these problems.

Potential improvements include removing unused functionality, reducing unnecessary scripts and deferring resources that aren’t required immediately.

A word of caution: Aggressive JavaScript optimisation can break menus, forms, sliders, tracking scripts and other interactive features.

Always test changes thoroughly, ideally in a staging environment, before deploying them to a live website.

Step 5: Review Caching and Hosting Performance

Sometimes the problem isn’t the website’s design or content. It’s the infrastructure supporting it.

Poor hosting performance, inefficient database queries or incorrect caching settings can significantly affect loading times.

For WordPress websites, performance improvements might include:

• Configuring server-side or page caching.
• Reviewing hosting resources.
• Using an appropriate content delivery network (CDN).
• Reducing unnecessary database overhead.
• Investigating slow plugins or server processes.

Caching plugins such as WP Rocket can assist with several performance-related tasks, but correct configuration is essential.

Installing a caching plugin doesn’t automatically resolve every performance issue.

Step 6: Evaluate Third-Party Scripts

Marketing technology can introduce its own performance challenges.

Google Tag Manager, analytics platforms, advertising pixels, cookie consent solutions, live chat widgets and embedded media may all contribute additional network requests or JavaScript processing.

Some are essential for business operations. Others may be redundant or incorrectly configured.

Rather than indiscriminately removing scripts, evaluate which technologies are necessary and whether their implementation can be improved.

A connected digital strategy should balance measurement requirements with website performance.

Why Your WordPress Website Might Be Slow

WordPress is a flexible and capable content management system, but its performance depends on how it is configured and maintained.

A slow WordPress website is rarely the result of WordPress itself.

More commonly, performance issues arise from a combination of:

• Excessive or poorly optimised plugins.
• Heavy themes and page-builder configurations.
• Large images and media files.
• Inefficient database operations.
• Inadequate hosting resources.
• Poorly configured caching.
• Unnecessary third-party scripts.
• Outdated or conflicting components.

Plugins should therefore be evaluated on their functionality, quality and actual performance impact rather than simply their number.

A website running numerous well-optimised plugins may outperform one using only a handful of resource-intensive extensions.

The key is identifying which components are genuinely creating bottlenecks.

Does Website Speed Affect SEO?

Yes, although the relationship requires some context.

Google’s ranking systems use Core Web Vitals as part of their broader consideration of page experience.

However, website speed is not a substitute for relevant content, strong technical SEO or genuine expertise.

A fast-loading website with poor content will not necessarily outrank a slower website that provides significantly more useful information.

Nevertheless, improving website performance can support several important objectives:

Better user experience: Visitors can access and interact with content more comfortably.

Reduced friction: Faster interactions can make browsing, form completion and purchasing easier.

Improved conversion opportunities: Removing delays and technical frustrations can help more visitors complete meaningful actions.

Stronger technical foundations: A well-optimised website supports a more reliable and accessible digital experience.

Website speed should therefore be treated as both a technical SEO consideration and a commercial performance issue.

How Often Should You Test Your Website?

PageSpeed Insights shouldn’t be something you use only when a website becomes noticeably slow.

Regular testing can help identify performance deterioration before it becomes a significant problem.

Consider running tests:

• After major WordPress, plugin or theme updates.
• Following substantial changes to page layouts.
• When introducing new marketing or analytics scripts.
• After launching new landing pages.
• During scheduled technical website audits.
• When Google Search Console reports Core Web Vitals problems.

Keep in mind that Lighthouse results can vary between tests.

For meaningful comparisons, test the same URLs under similar conditions and consider multiple runs.

Real-user Core Web Vitals data also reflects a rolling 28-day period, so improvements won’t necessarily appear immediately.

Don’t Optimise for the Score. Optimise for the User.

One of the most common mistakes in website optimisation is focusing exclusively on achieving a green PageSpeed Insights score.

A business might spend considerable time improving a performance score from 92 to 98 while overlooking more important problems, such as broken enquiry forms, confusing navigation or poor mobile usability.

Conversely, a page scoring 55 may have several straightforward technical issues that significantly affect how quickly visitors can access its content.

The objective should always be to prioritise improvements according to their impact on real users and business outcomes.

PageSpeed Insights provides the diagnostic information. A sound digital strategy determines what to do with it.

Is Your Website Performance Costing You Business?

A slow website isn’t always immediately obvious.

Pages might load quickly on your office connection while performing poorly for customers accessing them through mobile networks.

Visitors may abandon an enquiry before a form becomes responsive. Important content may appear too slowly, or unexpected layout shifts may disrupt the browsing experience.

Without proper testing, these problems can remain undetected.

A technical website audit helps establish whether loading speed, rendering issues, JavaScript execution or underlying infrastructure are affecting your website’s performance.

More importantly, it helps identify which improvements deserve attention first.

Let ALT Digital Help You Improve Your Website Performance

At ALT Digital, we understand that website performance isn’t simply about achieving a better technical score.

It’s about creating a faster, more reliable and effective digital experience that supports your marketing objectives.

Our website audits, technical SEO services and WordPress management solutions help businesses identify performance bottlenecks, address underlying technical issues and improve their digital foundations.

Whether your website is experiencing slow loading times, poor mobile performance or unexplained technical problems, we’ll help you understand what’s happening and where improvements can be made.

Your website should work as hard as your marketing does.

Contact ALT Digital to discuss a technical website audit and discover how improved website performance can support better digital outcomes.