When you open a web-page, the browser requests the HTML document from a server, parses its contents, and submits separate requests for any referenced resources. JCH Optimize uses the HTTP/2 Push feature to preload key requests to make your pages load faster.

Use the HTTP/2 Push feature to preload key requests

The component does this using the Link HTTP Header:

Link: </css/style.css>; rel="preload"; as="style"
                        

A benefit of specifying preload in the HTTP Header rather than the <link rel="preload"> is that the browser doesn't need to parse the document to discover iit, which can offer small improvements in some cases.

JCH Optimize will preload font files and images that are used above the folds, CSS files when the Optimize CSS Delivery feature is disabled, and JavaScript files without the defer or async attributes.