> As far as I’m aware, a TCP connection is still opened when using the cache, as well as TLS with all its overhead. If the cache control headers says it expire

> As far as I’m aware, a TCP connection is still opened when using the cache, as well as TLS with all its overhead. If the cache control headers says it expires in the future, the browser will not usually make any request, just load it from the disk. Hence a typical practice of setting a expiration date very far in the future, and just changing the URL when the resource is updated (thereby forcing the browser to request the new representation).