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.
LZF is currently available through PECL http://pecl.php.net/package/lzf.
If PEAR is available on your *nix-like system you can use the pear installer to install the LZF extension, by the following command: pear -v install lzf.
You can always download the tar.gz package and install LZF by hand:
You can pass --enable-lzf-better-compression to optimize LZF for space rather then speed.
Windows users can download the extension dll php_lzf.dll from http://snaps.php.net/win32/PECL_STABLE/.