Rules  1  2  3  4  5  6  7  8  9  10  11  12  13  14 
Rule 3 - Add an Expires Header
 Examples  1  2 
Example 1 - No Expires

Roundtrip response time:

This example contains six images, three scripts and one stylesheet that do not have a far future Expires header.1 Load the page several times using the "try it again" link and compare the response time to Example 2 - Far Future Expires. This example is slower because it has to make ten additional HTTP requests.

1 Browsers differ in how they handle components with no Expires header. Download behavior also varies depending on the cache settings chosen in the browser options. This example uses an Expires date in the past to guarantee that the browser behaves consistently. | contact SteveGreyhound, the 2nd fastest land animalThis is the companion website for High Performance Web Sites by Steve Souders.