There is a CPU column... anyway, it tells you all the necessary information. You can see which files on which vhosts are being accessed most at the time you notice the problems. Also, pay special attention to the Req column.
You might try using "time php /path/to/script.php" -- but that won't give you memory information. Do you really need memory though? Are you swapping? Just because you're processing a lot of information (high load averages), doesn't mean you have a memory leak or something.