The Windows Cache Extension for PHP is a PHP accelerator that is used to increase the speed of PHP code running on the Windows Operating System. The extension increases PHP performance by:

1. Caching the contents of PHP script files in shared memory, which helps to reduce the amount of file system I/O operations that is performed by the PHP engine. This is especially important when the PHP scripts are located on a remote UNC file share.
2. Caching the mappings between the relative file paths and corresponding absolute file paths. This reduces the amount of requests to file system when PHP scripts perform any file operations by using relative file paths.
3. Caching the compiled PHP opcode in shared memory to avoid the overhead of parsing and compiling the PHP source code for every request.

IMPORTANT: The Windows Cache Extension for PHP can only be used with the non-thread-safe builds of PHP.

You can download the extensions from here:

Windows Cache Extension 1.0 for PHP 5.2 Beta

Windows Cache Extension 1.0 for PHP 5.3 Beta