Minify Code

if ( !is_user_logged_in() ) { 
function sanitize_output($buffer) { 
    $search = array( 
        '/\>[^\S ]+/s',  // strip whitespaces after tags, except space 
        '/[^\S ]+\</s',  // strip whitespaces before tags, except space 
        '/(\s)+/s'       // shorten multiple whitespace sequences 
    ); 
    $replace = array( 
        '>', 
        '<', 
        '\\1' 
    ); 
    $buffer = preg_replace($search, $replace, $buffer); 
    return $buffer; 
} 
ob_start("sanitize_output"); 
} 


Source : https://www.quora.com/How-can-I-manually-speed-up-my-wordpress-site-without-plugins