If you are using php as the development language for your site then you will be aware that php is an interpreted language. This means that every time a page is requested from your server the corresponding php file needs to be compiled first before being run. This obviously creates a performance overhead. However, what if you could compile these files only once and then execute just the compiled codewhen a user requests a page?

Well, you can. There are a couple of free products available that can do this for you: eAccelerator, and Alternative PHP Cache (APC). Both of these do effectively the same thing by storing the compiled php opcode onto an area on the hard disk and then running this each time a page is called. However, eAccelerator also attempts to optimize the opcode for you in order to gain even further performance benefits.

One further benefit of using eAccelerator is that it provides content caching allowing you to cache your scripts output for predefined intervals. This is useful if the majority of your site is dynamically generated from a database, as it will minimize the number of database queries made by your application.

Using either of these packages will usually provide you with a performance increase somewhere around 40%, and of the two eAccelerator has been shown to outperform APC by about 13%. Although, APC is slated to be included in the forthcoming php version 6 which also makes it a good bet.

You can download eAccelerator here , and APC cache here.