PHP5 Utility timer for fast benchmarks of code

Timer.php

<?php

class Timer {

	protected static $start_time = 0.00;
	protected static $total_time = 0.00;

	public static function start() {
		self::$start_time = microtime(true);
	}

	public static function stop() {
		$time_end = microtime(true);
		$end_time = $time_end - self::$start_time;
		self::$total_time = $end_time + self::$total_time;
		return sprintf("%.3fs (%.3fs total)" ,$end_time, self::$total_time );
	}
}