In addition to dns-prefetch, you can take browser performance one step further by actually creating a new connection to a resource.
By initiating an early connection, which includes the DNS lookup, TCP handshake, and optional TLS negotiation, you allow the user agent to mask the high latency costs of establishing a connection.
- Firefox 39+ (Firefox 41 for crossorigin)
- Chrome 46+
<link rel="preconnect" href="//example.com" />
<link rel="preconnect" href="//cdn.example.com" crossorigin />