Minify PHP Output Buffer - Compress HTML output to a single line, then attempt gzip compression

ob_minify.php

<?php

/**
 * Smart Tidy/Gzip Output Buffer
 * Compress HTML output to a single line, then attempt gzip compression.
 * @param string $buffer
 * @param int $mode
 * @return string|false
 */
function ob_minify($buffer, $mode) {
    $search = array(
        '/<!--[^\[](.*?)-->/s' => '',
        //'/ +/' => ' ', // Old way to remove extra whitespace, wasn't catching everything
        '/\s{2,}/' => '', // New way catches everything, maybe that's too aggressive?
        //"/<!–\{(.*?)\}–>|<!–(.*?)–>|[\t\r\n]|<!–|–>|\/\/ <!–|\/\/ –>|<!\[CDATA\[|\/\/ \]\]>|\]\]>|\/\/\]\]>|\/\/<!\[CDATA\[/" => ''
        "/[\t\r\n]|<!–|–>|\/\/ <!–|\/\/ –>|<!\[CDATA\[|\/\/ \]\]>|\]\]>|\/\/\]\]>|\/\/<!\[CDATA\[/" => ''
    );
    $buffer = preg_replace(array_keys($search), array_values($search), $buffer);
    /* Only gzip for content with a min size of 860 bytes
     *
     * The reasons 860 bytes is the minimum size for compression is twofold: (1) The overhead of compressing an object
     * under 860 bytes outweighs performance gain. (2) Objects under 860 bytes can be transmitted via a single packet
     * anyway, so there isn't a compelling reason to compress them.
     */
    if (ob_get_length() >= 860) {
        return ob_gzhandler($buffer, $mode);
    }
    return $buffer;
}