I've had to do something similar before, and I believe the output of this command should help you: 

ps -eo pcpu,pid | sed '1d; s/^ *//; s/  */ /g;' | sort -nr

Update:
One assumption here is that process IDs don't get wrapped around in half an hour, but what are the chances of that?

Another update:
Thinking about it some more, since only one process can consume 75% of CPU at one time, you can append this piece to the pipeline above: 


| head -1

In reply to Re: Using Perl to find Process Hogs by dmitri
in thread Using Perl to find Process Hogs by Octavian

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