Missing preconnect hints for critical third-party domains

A preconnect hint is a line of code that tells the browser to start connecting to a third-party server (such as a font provider) in the background, before it actually needs anything from it. Without these hints, the browser waits until it discovers a resource is needed and then begins the connection — adding 100 to 300 milliseconds of delay on mobile, which slows your page load. Add a link element with rel="preconnect" for each critical third-party domain (such as fonts.googleapis.com) in your page's head section.