Guide: Tutorial on how to fix a slow WordPress website – 10 steps for better speed

A WordPress site that loads slowly can have issues due to several causes: images that are too large, lack of cache, plugins that consume many resources, unoptimized CSS and JavaScript, external scripts, slow hosting or an unsuitable WordPress configuration.

Before randomly installing optimization plugins, it is more efficient to identify the cause and check the result after each change.

In this tutorial you will go through step by step the main checks for identifying and optimizing a slow WordPress site.

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Step 1: Test site speed before changing anything

The first thing you need to do is measure the current performance of the site.

Do not start directly modifying plugins, CSS, JavaScript, or cache. First, you need a baseline value.

Test at least:

• the homepage;
• a service page;
• an article page;
• an important page for conversions;
• the mobile version;
• the desktop version.

Note the observed issues and obtained values. After optimization, you will be able to compare the results.

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Step 2: Check if the issue is general or only appears on certain pages

Do not assume the entire site is slow just because a single page loads slowly.

Open several types of pages and compare them.

If the homepage is slow, but articles are fast, the issue may be related to homepage-specific elements.

If all pages are slow, the common components must also be analyzed: hosting, cache, the theme, plugins, fonts, scripts, and the WordPress configuration.

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Step 3: Check images

Very large images are one of the frequent problems of Web pages.

A photo uploaded to the Media Library at a much higher resolution than the size at which it is displayed can unnecessarily increase the page size.

Check:

• file size;
• image resolution;
• the format used;
• images displayed above the fold;
• images loaded in sliders;
• images in CSS backgrounds.

For many modern projects, converting images into formats like WebP can reduce file size, but the actual result must be checked after optimization.

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Step 4: Enable caching

Caching allows reusing previously generated resources or pages, reducing the work the server has to perform for each visitor.

WordPress documents several levels of caching: page cache, browser cache, object cache, and server cache.

For a standard WordPress site, the first thing to check is whether a properly configured page cache system exists.

Important: do not install multiple cache plugins just because each promises to speed up the site. Two systems that modify the same mechanisms can conflict.

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Step 5: Check installed plugins

Each plugin adds functionality, and some plugins may add CSS, JavaScript, database queries, or other processes that affect performance.

Go to:

WordPress → Plugins → Installed Plugins

Check if there are:

• plugins you no longer use;
• duplicate plugins;
• multiple cache plugins;
• optimization plugins that perform the same operations;
• abandoned or unupdated plugins.

Do not deactivate important components of the site without checking what function they perform.

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Step 6: Test if a plugin is causing slowdown

If you suspect a plugin, do not delete it immediately.

First perform a check and, if possible, test in a safe environment or after making a backup.

Temporarily deactivate the suspicious plugin and test the same page again.

If the performance changes significantly, you have identified a potential factor.

Repeat the method for other plugins when necessary.

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Step 7: Check CSS and JavaScript

A site can be slow even if the images are optimised.

The theme, page builder, and plugins can load many CSS and JavaScript files.

Issues can occur when loading:

• unnecessary CSS files;
• scripts that are not required on certain pages;
• bulky JavaScript libraries;
• third-party scripts;
• duplicate files.

Minification can reduce the size of certain files, but it must be tested after activation.

Do not enable all aggressive optimisation options simultaneously without checking the site after each change.

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Step 8: Check external fonts and scripts

Fonts, analytics services, ads, widgets, chats, maps, and other external services can add extra requests.

Identify the external elements loaded on each page.

Ask yourself for each one:

• Is it necessary?
• Is it used on this page?
• Can it be loaded only where it is needed?
• Is there a simpler alternative?

Removing an unnecessary feature can be more efficient than trying to aggressively optimise its code.

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Step 9: Check hosting and server response time

Not all speed issues can be solved from WordPress.

If the server responds slowly, image optimisation or CSS minification will not completely solve the problem.

Check:

• server response time;
• available resources;
• PHP version;
• server configuration;
• server cache;
• potential resource limits;
• server load during peak periods.

If the issue is at the hosting level, WordPress optimisation may have limited effects.

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Step 10: Test again after each change

After making changes, do not automatically assume the site is faster.

Run the tests again and compare the results with the initial values.

Check both performance and functionality.

A site may get a better result on a performance test, but have issues with:

• menu;
• forms;
• sliders;
• galleries;
• shopping cart;
• checkout;
• login;
• pop-up windows;
• interactive elements.

Therefore, after every major change, the site functionality must also be checked.

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What NOT to do when optimising WordPress

• Do not install multiple caching plugins without checking if they overlap.
• Do not enable all optimisation options simultaneously.
• Do not delete plugins without checking which functions depend on them.
• Do not modify site files without a backup.
• Do not optimise for a single test only and ignore the real user experience.
• Do not assume that a higher score automatically means a perfect site.
• Do not remove important features just for a few extra PageSpeed points.

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How to check if the optimisation worked

After completing the changes, test the same pages you tested at the beginning again.

Compare:

Checked element	Before	After
Loading time	Initial value	Value after optimisation
Page size	Initial value	Value after optimisation
Number of requests	Initial value	Value after optimisation
Core Web Vitals	Initial result	Result after optimisation

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Final checklist for a slow WordPress site

Check	Status
Speed was measured before optimisation	☐
Images were checked	☐
Cache was checked	☐
Plugins were checked	☐
CSS and JavaScript were analysed	☐
Fonts and external scripts were checked	☐
Hosting was checked	☐
The site was tested on mobile	☐
Site functions were tested after optimisation	☐
Performance tests were repeated	☐

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Frequently asked questions

Why is my WordPress site slow?

The cause can differ from one site to another. Possible factors include large images, lack of caching, plugins, the theme, CSS, JavaScript, external scripts, the database, hosting or server configuration.

Does a caching plugin always solve the problem?

No. Caching can significantly improve the performance of certain sites, but it cannot eliminate all the causes of a slow site. WordPress documents caching as one of the important optimisation components, alongside other mechanisms. :chatgpt-content-reference{index=”2″}

Do all images need to be optimised?

Images must be analysed according to size, format and how they are used. Changing the format is not enough; the actual file size and the effect on page loading must also be checked.

Why is the site fast on a computer, but slow on a phone?

The mobile version may load the same resources on a connection and device with more limited resources. Therefore, performance must be checked separately on mobile and desktop.

Should I only track the PageSpeed score?

No. The score is an indicator, but loading time, Core Web Vitals, loaded resources and the actual user experience must also be analysed.

Can I optimise WordPress without breaking the site?

Yes, but changes must be made in a controlled manner. It is recommended that you make a backup and test the site after major changes. Some CSS and JavaScript optimisations can affect the functionality of certain themes, plugins or forms.

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Do you need help?

If your WordPress site loads slowly, has performance issues or you want to identify and fix technical issues affecting its speed and visibility, iTechServiceTM can analyse the structure, performance and technical elements of the site.

View service SEO optimisation.