Minimize the number of CSS files to reduce the number of HTTP requests. If several style sheets are used on all of the website’s pages, concatenate them into one single file.

Some CMS and frameworks offer ways to do such optimization automatically. The HTTP server can also be configured to compress and reduce the size of style sheets (see best practice #79).

Modifying the DOM (Document Object Model) as you traverse it risks making the loop highly resource-expensive, especially in terms of CPU usage. An infinite loop, which consumes a huge amount of resources, might be generated if we add elements at the same time as we traverse it. It is thus highly recommended to NOT perform such edits.