JavaScript:
//src - http://stackoverflow.com/a/18336968
//place this before any script you want to calculate time
$time_start = microtime(true);
// do something
// Display Script End time
$time_end = microtime(true);
//dividing with 60 will give the execution time in minutes other wise seconds
$execution_time = ($time_end - $time_start)/60;
//execution time of the script
echo '[B]Total Execution Time:</b> '.$execution_time.' Mins';