Since the work is being done by a PL/SQL stored procedure, which (of course) returns its results instantly on the Windows box, you know that the bottleneck cannot be either the PL/SQL nor the size of the database.

Since the delays you are experiencing are “eight or nine seconds,” the cause simply has to be physical in nature ... that is to say, networking, or quite possibly a timeout. As others have said, you need to trace it, look at server-logs and so forth. There isn't a “programming error” in this world that's going to cause this kind of a delay. So, don't stare at your code, or at Perl. The problem isn't there.