There’re a whole 5 different methods of preloading, and all of them are suitable for different goals. Here’re what these methods do, in brief:
<link rel="dns-prefetch"> instructs the browser to make a DNS request for a server’s IP address in advance. This is useful for CDNs, Google Fonts, and all other cases when you know you’ll need a resource in a short time, know the domain it’s hosted at, but don’t know its exact path. In this case, resolving the server’s IP address in advance would save you from 50 to 300 ms.
... read the whole story at 3perf.com.
<link rel="preconnect"> instructs the browser to perform the connection to a server in advance. It’s useful in the same cases when