Unused CSS – A Major Cause of Slow Webpage Loading

Unused CSS – A Major Cause of Slow Webpage Loading

Do you know there is nearly 35 % of CSS code that is completely needless in a website development, and causes delay in webpage loading? The CSS files of the website may contain various redundant rules that are no longer being utilized by any content on the web page. They increase the page loading time of the site and affect its performance by causing the browser to parse additional rules. There are ways to minify these codes without affecting how resource file is processed by the web browser. If you can remove that unnecessary or redundant date effectively, you actually help the performance win.

Online Tools To Remove Unused CSS

Most people care about performance while working on a project and believe that reducing file size is handy to boost performance. You can easily add unbeatable functionality to your website by using numerous online tools such as UnusedCSS that are designed to help you find and remove unused CSS from your site. These tools first need to perform analysis in order to be able to determine what is unused and what is not. They navigate through your site following each internal link, evaluate all webpages, and provide a list of unused CSS selectors in your stylesheets.

You can also choose one of the ways to do that analysis. For instance, reduce a page of your website to obtain the complete DOM and CSSOM. This will give you a range of all the selectors present in your CSS. Loop over these selectors and run a queryselector in the DOM and find out if it displays any match. If it does not, this signifies that it is unused CSS selector. Once found, use appropriate tools to reduce unused CSS in your website in order to optimize the overall performance of the site.

The best part of CSS cleanser tools is that they enable you to find and remove unused CSS rules without having to deal with them manually. They are compatible with all types of websites including Bootstrap and WordPress. With such tools, you can log into your site and set a custom-made user agent that will crawl through your website to make complete analysis. A visual diff of the cleaned CSS file is displayed on your screen after all the unused CSS selectors are found and removed from the stylesheets.


The loading speed of a website is one of the most important features for its success. A faster site not only leads to more sales but also helps you achieve your objectives within a business. Often JavaScript and CSS increase webpage loading time by redirecting extra HTTP requests to the web server. These scripts can be minified to increase the website speed significantly. There are a number of dedicated tools and script compressing services that can be used to find and remove unnecessary elements such as unused CSS from the script to compress the file size. Less CSS code in the web script means faster downloading of a website. Also, it ensures less time for a web browser to analyze and display a web page.

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