This PECL extension
is not bundled with PHP.
  Information for installing this PECL extension may be
found in the manual chapter titled Installation 
of PECL extensions. 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.
 
  Windows users will enable php_lzf.dll inside
  of php.ini in order to use these functions.
  You may download this PECL
extension DLL from the 
PHP Downloads page or at 
http://snaps.php.net/.