Also, unless ./alert_main.pl actually does something with the database this is never going to improve the performance, if the bottleneck is in waiting for the rows to arrive.
./alert_main.pl makes the calls to the db and waits for the response. I was hoping that I could speed up the whole app by running n copies of 'alert_main.pl' simultaneously each of which would have a separate piece of the whole process.
Comment on Re^2: fork-ing : my lack of understanding
It's possible that some sort of locking / transaction scheme is making concurrent queries slower than running consecutive queries. The answer probably lies in examining what alert_main.pl is doing exactly