Chapter 6. Caches and Handlers

Running PHP has quite a high cost, but in return we gain the benefit of a very powerful and flexible language. The combination of power and high cost suggests that for any code that will be executed frequently, we should use the power of PHP to aid efficiency. The greatest efficiency is gained by streamlined design. After all, not doing things at all is always the best way to achieve efficiency. Designing with a broad canvas, so as to solve a number of problems with a single mechanism, also helps. And one particular device the cache provides a way to store data that has been partly or wholly processed and can be used again. This obviates doing the processing over again, which can lead to great efficiency gains.

The discussion here is entirely about server-side caching. In general, a CMS is serving dynamic pages that may change without warning. It is usually undesirable for proxies between the server and the client to hold copies of pages and there are severe...