Minify HTML

<?php

function minify_html($buffer) {

  // Remove comments

  $buffer = preg_replace('//', '', $buffer);

  // Remove whitespace

  $buffer = preg_replace('/^\s+|\s+$/m', '', $buffer); // Trim lines

  $buffer = preg_replace('/\s+/', ' ', $buffer);       // Replace multiple spaces with single space

  // More aggressive minification (use with caution - can break things)

  // $buffer = preg_replace('/\s+/', '', $buffer);  // Remove all whitespace

  return $buffer;

}

function minify_html_output() {

  ob_start("minify_html");

}

add_action('template_redirect', 'minify_html_output');

?>