LZF is a very fast compression algorithm, ideal for saving space with only slight speed cost. It can be optimized for speed or space at the time of compilation.
This PECL extension is not bundled with PHP. Additional information such as new releases, downloads, source files, maintainer information, and a CHANGELOG, can be located here: http://pecl.php.net/package/lzf.
In order to use these functions you must compile PHP with lzf support by using the --with-lzf[=DIR] configure option. You may also pass --enable-lzf-better-compression to optimize LZF for space rather then speed.