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7 Common Website Performance Issues and How to Fix Them


Website performance is one of the most important user experience aspects from a user satisfaction and SEO perspective. At Clio, we specialize in helping clients improve their website performance metrics.

In this article, we will discuss the most common website performance issues that we encounter, and give you some tips on how to fix them.

Let’s dive in.

What is website performance?

Website performance is all about how quickly and smoothly your website loads for visitors.

Website performance is about how easy it is for people to find what they’re looking for, and how well the website works on different devices (mobile, desktop, and tablet).

To improve website performance, web developers can make changes to the website’s code and design to help distribute the website’s content to visitors more quickly. They can also monitor the website and make sure it’s running smoothly and fix any issues that arise.

As a business owner, you don’t need to understand all the technical details, but it’s good to be aware of the importance of website performance and how it can affect your business. You can work with a web developer or an agency to make sure your website is running well and providing a good experience for your visitors.

Website performance improves conversions, SEO, and visitor satisfaction. In fact, according to research, over half of the visitors will abandon a website that takes longer than 3s to load. 

This is why speeding up your website is especially important if you are selling products or promoting your services.


Common website performance issues

We help clients troubleshoot and resolve performance issues all the time. Here are the 7 most common issues we encounter when working with clients:

  1. No browser caching
  2. Render-blocking resources
  3. Inefficient code
  4. No content delivery network (CDN)
  5. Third-party assets
  6. Inefficient images
  7. Unused CSS and JavaScript

Let’s dig into each of these in detail and see how we can fix them.

#1 – Lack of browser caching

What is browser caching?

YouTube video

Browser caching stores certain elements of a website, such as images, CSS, and JavaScript files, in the browser’s cache. This allows the browser to quickly access these resources the next time the user visits the website, which can help to speed up page load times.

Caching all types of websites is an excellent idea to improve performance and load speeds, especially for WordPress websites. WordPress websites require a database that stores information so they are slower than static websites for that reason and require more server horsepower. Storing this information in the cache speeds up the load times because it eliminates round trips to the database.

There are several types of caching approaches and they depend on what your hosting provider supports. We recommend several hosting providers due to their excellent caching, security, and performance features.

Besides browser caching, there is also server-side caching, object caching, and CDN caching, and they can sometimes be used in combination. Each type of caching has its own advantages and disadvantages, and the specific type used may depend on the requirements of the website and the needs of the user.

How to fix:

The simplest way is to utilize caching provided by your hosting provider. Some hosting providers, such as Kinsta, SiteGround, and Cloudways, have their own caching plugins that you can configure to speed up your website.

We also recommend using WP Rocket in order to implement browser caching and further improve the speed of your website.

#2 – Render-blocking resources

What is render-blocking when it comes to web development?

Render blocking is when certain website resources, such as CSS stylesheets or JavaScript files, prevent or delay the rendering of a webpage. When a browser loads a webpage, it must download, parse, and execute these resources before it can display the content to the user.

If these resources are not properly optimized or are loaded, they can block or slow down the rendering process, resulting in a poor user experience.

Two common types of render-blocking resources are:

  1. CSS stylesheets: CSS is used to style webpages and can be embedded within the HTML, linked as an external file, or loaded via JavaScript. If a browser encounters a linked external stylesheet, it must download and parse the file before it can continue rendering the page. This can cause delays if the stylesheet is large or if the server is slow to respond.
  2. JavaScript files: When a browser encounters a JavaScript tag or code, it has to download, parse, and execute the JavaScript before it can continue rendering the page. This can be problematic if the script is large, slow to download, or takes a long time to execute.

To learn more about render-blocking, you can check out this article on the Chrome Developer blog.

How to fix:

To minimize render-blocking issues, web developers can try to:

  1. Minify and compress resources: Reducing the file size of CSS and JavaScript files can help decrease download times and speed up rendering.
  2. Inline critical CSS: Inlining the most important CSS rules directly into the HTML can help ensure that above-the-fold content is styled quickly, improving perceived performance.
  3. Async and defer attributes: Adding the ‘async’ or ‘defer’ attribute to script tags can change how JavaScript files are loaded and executed, allowing the browser to continue rendering the page while downloading and parsing the scripts.
  4. Prioritizing the loading of critical resources: Using tools like ‘preload’ and ‘prefetch’ can help prioritize the loading of important resources and improve page load times.
  5. Code splitting: Breaking up large JavaScript files into smaller, more manageable pieces can reduce the impact of render-blocking scripts.

Most modern WordPress caching plugins can help resolve these render-blocking issues. This is a fairly complex issue, which will require enlisting help from a web developer.

By addressing render-blocking problems, web developers can improve the performance of their websites and create a better user experience.


#3 – Inefficient code

Inefficient code is code that is poorly written and which impacts the performance of a website negatively. It can slow a website down by loading unnecessary functionality, or it can generate errors on the website. Unfortunately, this is the hardest issue to resolve and troubleshoot because it’s hard to identify and fix.

If you are using WordPress, there are several ways to identify inefficient code, but they require some web development experience.

Here are some tips that can help you identify poor code on a WordPress website:

  1. Performance monitoring and profiling tools: Tools like Query Monitor or Debug Bar allow you to monitor the performance of your WordPress site, identifying slow database queries, PHP errors, or other issues that may indicate poorly written code.
  2. Browser developer tools: Modern web browsers come with built-in developer tools that can help you diagnose performance issues. These tools can help you analyze network requests, inspect CSS and JavaScript files, and identify slow or inefficient code.
  3. Code review: Manually reviewing the code of plugins, themes, and customizations can help you spot inefficiencies, redundancies, or poorly written code. Look for adherence to WordPress coding standards, proper use of hooks and filters, and optimized database queries.
  4. Compare performance with and without plugins/themes: Deactivate plugins one by one or switch to a default WordPress theme (e.g., Twenty Twenty Two) to isolate performance issues. If your website’s performance improves significantly after deactivating a specific plugin or theme, it might be a sign of poorly written code.
  5. Check error logs: Review your server’s error logs for PHP errors, warnings, or notices. These logs can provide valuable information about problematic code, conflicts, or other issues that need to be addressed.
  6. Analyze page load times: Tools like Google PageSpeed Insights, GTmetrix, or WebPageTest can help you analyze the performance of your website, including identifying render-blocking resources or other issues that may be caused by poorly written code.

How to fix:

We recommend using only fast and efficient plugins and themes to avoid these issues in the first place. Working with a professional development agency can also help you avoid these issues or resolve them on an existing website.

#4 – No Content Delivery Network (CDN)

A lot of website owners don’t utilize a Content Delivery Network, but it’s one of the easiest ways to improve performance.

What is a Content Delivery Network?

A Content Delivery Network (CDN) is a geographically distributed network of servers designed to deliver websites more efficiently to users. The primary goal of a CDN is to improve the performance, reliability, and security of a website.

When a user requests a website, the CDN will deliver the static assets from the nearest server located to the user, which reduces the latency and the load time of the content. This results in faster page load times, improved user experience, and reduced load on the server.

Some of the benefits of using a CDN include:

  1. Improved performance: By serving content from the nearest edge server, CDNs reduce latency and provide faster load times for users, enhancing their experience on the website.
  2. Scalability: CDNs can handle a large number of simultaneous requests, making it easier for websites to manage traffic spikes and high volumes of users without overloading the origin server.
  3. Reliability: CDNs use a distributed network of servers, which means that if one server goes down, the content can still be served from another server in the network. This increases the reliability and uptime of the website.
  4. Security: Many CDNs provide additional security features, such as DDoS protection, web application firewalls (WAF), and secure content delivery using HTTPS. These features can help protect your website from attacks and maintain the security of your users’ data.
  5. Global reach: CDNs have edge servers located in multiple regions worldwide, ensuring that users from different geographical locations can access your website’s content quickly and efficiently.

As you can see, there are many benefits to utilizing a CDN service, especially if it’s serving content to users that are geographically dispersed.

How to fix:

Implementing a Content Delivery Network is relatively easy. Most hosting providers offer their own CDN services as an addon (which sometimes includes an additional fee).

If your hosting provider doesn’t offer a CDN, you can use the free service from Cloudflare. Setting this up involves changing your domain settings, which may require a web developer / administrator.


#5 – Third-party assets

Adding a social sharing plugin or a tracking code to your website may seem harmless, but it can significantly slow down your website. This is another common issue that we see when troubleshooting and fixing performance issues.

What are third-party or external assets when it comes to web development?

Third-party or external assets in website development refer to resources that are loaded from external sources, rather than being hosted on your own server or domain.

These resources can include various types of files, such as:

  1. JavaScript libraries and frameworks: Many websites use popular JavaScript libraries and frameworks like jQuery, React, or Angular.
  2. CSS libraries and frameworks: Similarly, websites may use external CSS libraries or frameworks like Bootstrap, Bulma, or Font Awesome for styling and typography.
  3. Fonts: Web fonts, such as those provided by Google Fonts or Adobe Fonts, can be loaded from external sources to provide consistent typography across different devices and browsers.
  4. Images and videos: Some websites host their media files on external platforms like Imgur, YouTube, or Vimeo to save bandwidth and storage space on their own server.
  5. Analytics and tracking scripts: Services like Google Analytics, Facebook Pixel, or Hotjar provide tracking scripts that are loaded externally to track user behavior and gather data for analysis.
  6. Advertising and marketing scripts: Ads, affiliate marketing scripts, or conversion tracking scripts from platforms like Google Ads or Facebook Ads are often loaded externally.
  7. Widgets and embedded content: Social media widgets, comment systems like Disqus, or embedded content from platforms like Instagram or Twitter can also be considered third-party assets.

How to fix:

To minimize the impact of third-party assets on your website’s performance, you can:

  1. Scrutinize each third-party asset and remove any that are not critical to your website’s functionality or user experience (less is more).
  2. Optimize the loading of third-party assets by using async or defer attributes for JavaScript files, inlining critical CSS, and deferring the loading of non-critical assets (performance plugins can help).
  3. Monitor the performance of third-party assets using tools like Google PageSpeed Insights, GTmetrix, or WebPageTest to identify any bottlenecks or slowdowns caused by these resources.
  4. Consider self-hosting critical assets, such as fonts or essential JavaScript libraries, to reduce reliance on external sources and gain more control over the performance of your website.

The good news is, these issues are avoidable and can be resolved by limiting the use of WordPress plugins and tracking codes. Performance plugins such as WP Rocket and Perfmatters can also help alleviate these issues by hosting fonts and tracking codes on your local server.

#6 – Inefficient images

Inefficient images can severely impact the performance of your website. Yes, we all want great-looking images to showcase our brand, but finding a balance between file size and quality is key.

This is one of the most common website performance issues that we see when troubleshooting slow websites. The good news is, that this is also one of the easiest issues to fix.

How to fix:

Here are a few tips to help you reduce the size of your images, which can help a website load much faster on all devices:

  1. Resize your images so that they are not larger than you need them to be. For example, your image may not need to be 2000 pixels wide if you are using it in a small section of a website layout. Reduce the size of the image and the file size will also be reduced.
  2. Compress the image using one of the common and free tools such as tinypng.
  3. Convert the image to a more efficient file type such as webp (instead of jpeg or png). You can also do this for free using convertio or by using a WordPress plugin such as ShortPixel or Imagify.
  4. Lazy-load images (meaning that they aren’t loaded until the user scrolls to that part of the website) using code or using a performance plugin such as WP Rocket.

Using these improvements can significantly cut down on your inefficient images and help you speed up your website load times.


#7 – Unused CSS and JavaScript

Unused JavaScript and CSS refer to the code within your website’s JavaScript files and stylesheets that are not being utilized or needed for the proper functioning or display of your website.

This can slow down your website because of the large size of the assets (files) and the time it takes for the browser to parse and execute them.

Unused CSS and JavaScript files are present when too many plugins are used or the theme that a website is using is inefficient. Having this issue on your WordPress website can lead to the following performance issues:

  1. Larger file sizes: Unused code contributes to larger file sizes, increasing the time it takes to download and render these files.
  2. Slower page load times: The additional time required to download, parse, and execute unused JavaScript and CSS can result in slower page load times, negatively affecting user experience and search engine rankings.
  3. Increased complexity: Unused code can make it more difficult to maintain and update your website’s codebase, potentially leading to confusion, errors, or conflicts.

How to fix:

Consider the following strategies to fix this issue and improve your website performance:

  1. Audit your plugins: Evaluate the necessity of each plugin and remove any that are no longer needed or that contribute to excessive unused code.
  2. Audit your theme: Make sure that you are using a fast and efficient theme that doesn’t add code bloat. If your theme is slow, replace it with a faster theme.
  3. Optimize your code: Manually review your JavaScript and CSS files to identify and remove unused portions. WP Rocket and other performance plugins can also remove unused CSS code.
  4. Load only necessary assets: Ensure that your website only loads the JavaScript and CSS files it needs. For example, if a plugin or theme has multiple stylesheets, enqueue only the ones that are relevant to your website.
  5. Minify and compress your files: Minifying and compressing your JavaScript and CSS files can help reduce their size, mitigating the impact of unused code on your website’s performance.

By addressing unused JavaScript and CSS on your WordPress website, you can improve your site’s performance, user experience, and maintainability.

Common Website Performance Issues – Conclusion

Identifying performance issues early during your website development journey makes it easy to troubleshoot and fix them before they impact your users. But don’t fret, most of these are fixable no matter where your website is at.

We have helped many clients identify and fix common website performance issues, and this comprehensive guide can point you in the right direction if you want to troubleshoot these on your own.

Why Clio

We hope that you enjoyed reading about these common website performance issues and fixes. Our recommendations and techniques are based on years of experience helping businesses just like yours.

At Clio, we have helped many clients improve their speed scores. We have been developing websites and providing website maintenance services since 2007.

Contact us if you would like us to help you speed up your WordPress website.


Do you have any tips on how to improve website performance?

You can improve website performance by using fast and efficient themes, compressing your images, and not using too many plugins. For more tips, check out this article.

Tips on how to measure website performance?

You can measure website performance using Google’s PageSpeed Insights, GTmetrix, or All of these tools are free and can be used to identify and help you fix performance issues.

Are there any tools that can track website performance?

Only GTMetrix offers scheduled performance tests that can be ran on a weekly basis. SEO tools such as ahrefs and Semrush also monitor website performance as part of their technical SEO audit.

About the author

Nat Miletic is the founder of Clio Websites, a Calgary-based web design company. Nat writes about WordPress, SEO, and responsive web design.

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