In case your dbas need information on the Config file. In particular, look at:

1. -iqgovern Number of concurrent queries (default is 2*num_cpu+10)
2. -gm Number of connections that can be active at one time

You might be running into blocking locks if the parallel runs of your Perl code are hitting the same pages.

As far as Perl goes, you may want to enable DBI Tracing to determine if there is something funky going on.