String sanitization/filtering optimization in PHP

string-sanitization-optimize.php

<?php
/**
 * This class is our wrapper class to fix the 
 * inherent slowness of the parent class
 */
class Clean extends Sanitize {
    public static function xss($string)
    {
        // base case
        if (!preg_match('/[^a-zA-Z0-9_\-.\s?!,]/', $string)) {
            return $string;
        }

        // complex input requires complex sanitization
        return parent::xss($string);
    }
}

/**
 * This class is a placeholder example of a large, 
 * bulky sanitizer/filter.
 */
class Sanitize {
    public static function xss($string)
    {
        // crazy amounts of string replacement,
        // regular expressions, and 
    }
}