/**
 * @param $string (X)HTML document string
 * @return string
 * @todo benchmark/optimize performance
 */
private function minimizeHTML($string) {
   // will remove tabs, line breaks and extra white spaces
   $r = preg_replace(array('/\r/','/\n/','/
/','/\t/'),'',$string);
   $r = preg_replace('/\s\s+/',' ',$out);
   return $r;
}

/**
 * @param $string (X)HTML document string
 * @return string
 * @todo benchmark/optimize performance
 */
private function minimizeHTML($string) {
   // will remove tabs, line breaks and extra white spaces
   $r = preg_replace(array('/\r/','/\n/','/
/','/\t/'),'',$string);
   $r = preg_replace(array('/\s\s+/'),' ',$out);
   return $r;
}

/**
 * @param $string (X)HTML document string
 * @return string
 * @todo benchmark/optimize performance
 */
private function minimizeHTML($string) {
   // will remove tabs, line breaks and extra white spaces
   $out = preg_replace(array('/\r/','/\n/','/
/','/\t/'),'',$dom);
   $out = preg_replace(array('/\s\s+/'),' ',$out);
   return $out;
}

i know these regex stuff is rather slow, but still i like having slim documents. (don't forget to use gzip compression on all text docs)

HTML compression // white space removal

php, line

PHP