Remove Unused CSS (Deprecated)

As we have touched on in previous sections, when user requests a web page, the goal of the browser is to load and analyze all the HTML, CSS, and JavaScript needed to display the page. Again, the reasoning behind this is that if the browser began to show content before styles have been processed, it would look like a mess to the user because there are various rules that would eventually need to be applied. Additionally, if those stylesheets are external, and cached, the rendering is paused until the browser can load the stylesheet(s), which ends up causing a bottleneck and delaying the other loading of other page elements and scripts.

There are a few different methods to reduce the amount of CSS on your pages. One of the ways to optimize this process is to ensure as you are creating new pages that the CSS is optimized during the building process. That will end up saving you a lot of time later. Another method is to remove any CSS rules that are obsolete. There are third-party tools that can crawl your pages and determine if the CSS on the page can be optimized further.

And in addition to that, asynchronous loading, which we discussed in an earlier section, can be implemented to load CSS content that is not necessary for anything above-the-fold. You are not necessarily removing it from the page, but to the user, the page is loading fast and not being slowed down by any CSS. Removing CSS can be a frightening task. No one likes to remove anything because it might break something further down the stream, so find a tool, or someone who is extremely knowledgeable with your site to make these changes.