Css style

CSS Performance Optimization in 5 Easy Steps

An often overlooked website performance bottleneck occurs in the processing of cascading style sheets and the subsequent application of CSS selectors on the document object model of a web page.

To make web pages render faster and improve end-user experience, consider these five CSS performance optimization tips.

1. Use inline styles

If a given style is only used on one specific page element, such as an image slider or carousel, and that component is only used on a few pages of the site, use an inline style at instead of a universally loaded CSS. file. This will not only reduce the size of the external stylesheet, but also the number of CSS selector evaluations that occur on pages that don’t use the component.

2. Use specific styles

Do not apply styles to universal selectors, descendant selectors, and top-level HTML elements. This can trigger many Boolean evaluations. Instead, optimize CSS performance with selections on a finer element, such as a single class style.

3. Optimize CSS with WebComponents

WebComponents are self-contained and reduce the need for shared CSS and JavaScript

the WebComponents Framework is a relatively new, standards-based approach to building reusable components where JavaScript and styles are self-contained and isolated. When you keep styles required by a component outside of a globally shared CSS file, you won’t see any performance effect on other areas of the site where unused styling applications would consume clock cycles unnecessarily.

4. Split Your CSS Files

If many of your CSS files are tailored to a specific browser or device, break those styles into multiple CSS files. When running, load only those that are needed.

This CSS performance optimization trick will require either client-side JavaScript processing or server-side processing, but the benefits to users are worth it.

For example, if mobile and desktop renderings are very different, this can potentially reduce the number of Document Object Model (DOM) evaluations by 50% on each device type.

5. Reduce the size of your DOM

The tricks used to split your CSS file can also be used to reduce the size of your DOM.

Another CSS performance optimization trick is similar to splitting a CSS file into multiple device-specific files. Instead, you can also reduce the size of the web page itself, reduce the number of DOM elements in the HTML, and subsequently speed up client-side rendering.

However, the problem with CSS processing is not just the number of styles that need to be applied to a page, but also the number of DOM elements on the actual page. Many modern web pages that use responsive design load HTML source for the mobile and desktop experience with every page request. Instead, use client-side JavaScript or even server-side technology to ensure extraneous HTML code isn’t loaded onto a page that would never use it. This can greatly reduce the size of the DOM as well as the number of stylesheet evaluations the page has to go through.

Style sheets are a modern website developer’s best friend, but they often come with a hidden performance cost. Follow these five CSS performance optimization suggestions and reduce the possibility of your CSS selectors being the performance bottleneck on your website.