Simply use the LARAVEL_START constant for calculation page generation time in profiler.

laravel/profiling/profiler.php

@@ -15,15 +15,6 @@ class Profiler {
 	 */
 	protected static $data = array('queries' => array(), 'logs' => array());
 	
-	/**
-	 * The time when the profiler was setup.
-	 *
-	 * This is used for generating the total page rendering time.
-	 *
-	 * @var float
-	 */
-	protected static $start_time;
-
 	/**
 	 * Get the rendered contents of the Profiler.
 	 *
@@ -37,10 +28,7 @@ class Profiler {
 		// type applications, so we will not send anything in those scenarios.
 		if ( ! Request::ajax())
 		{
-			if (static::$start_time)
-			{
-				static::$data['time'] = number_format((microtime(true) - static::$start_time) * 1000, 2);
-			}
+			static::$data['time'] = number_format((microtime(true) - LARAVEL_START) * 1000, 2);
 			return render('path: '.__DIR__.'/template'.BLADE_EXT, static::$data);
 		}
 	}
@@ -80,9 +68,6 @@ class Profiler {
 	 */
 	public static function attach()
 	{
-		// Record when the profiler was setup (as a rough measure for render time)
-		static::$start_time = microtime(true);
-		
 		// First we'll attach to the query and log events. These allow us to catch
 		// all of the SQL queries and log messages that come through Laravel,
 		// and we will pass them onto the Profiler for simple storage.