A simple "StopWatch" class to measure PHP execution time. The class can handle multiple separate timers at the same time.

StopWatch.php

<?php

/**
 * A simple "StopWatch" class to measure PHP execution time.
 * The class can handle multiple separate timers at the same time.
 */
class StopWatch {
  /**
   * @var $start float The start time of the StopWatch
   */
  private static $startTimes = array();

  /**
   * Start the timer
   *
   * @param string $timerName string The name of the timer
   *
   * @return void
   */
  public static function start($timerName = 'default') {
    self::$startTimes[$timerName] = microtime(true);
  }

  /**
   * Get the elapsed time in seconds
   *
   * @param string $timerName string The name of the timer to start
   *
   * @return float The elapsed time since start() was called
   */
  public static function elapsed($timerName = 'default') {
    return microtime(true) - self::$startTimes[$timerName];
  }

  /**
   * Returns the elapsed time in a meaningful readable message
   *
   * @param string $timerName
   *
   * @return string
   */
  public static function describe($timerName = 'default') {
    return sprintf("StopWatch: '%s' operation completed in %s seconds", $timerName, StopWatch::elapsed($timerName));
  }

  /**
   * Outputs the elapsed time in a meaningful readable message
   *
   * @param string $timerName
   */
  public static function log($timerName = 'default') {
    print_r(self::describe($timerName) . "\n");
  }

  /**
   * Removes all timers
   */
  public static function flush(){
    self::$startTimes = array();
  }
}