EBS XML Publisher Report Bursting Program slow performance

I've inherited some concurrent programs that are submitted individually and then burst to an email address.  Today there were 356 of these request submitted concurrently in a matter of minutes.  ALL of the submitted concurrent programs themselves completed in less than 7 minutes.  Then each of these submitted an individual request to "XML Publisher Report Bursting Program".  These spawned child requests took 4 and a half hours to complete!  At first they were taking a few seconds to complete, but as more and more jobs were submitted (over just a few minutes) it bogged down the concurrent manager.  I had