Parallel DELETE on Partitioned Table with Domain Index

I have an application that runs a DELETE statement on single Partition, but with PARALLEL 8. The table also has Domain Index -- I haven't been told if it is Partitioned or not. The DELETE runs slowly. I'm trying to convince the DBA / Developer
(I have no access to the database) to run the DELETE without the PARALLEL.
(The PARALLEL 8 all operate within the *same* partition).

On a separate Test database without the Domain Index, the same DELETE, with PARALLEL, I have been told, runs very fast. So, the team suspects the Domain Index. I suspect contention on the Domain Index.

Any notes / stories that I can use ?

Hemant K Chitale
http://hemantoracledba.blogspot.com

"A 'No' uttered from the deepest conviction is better than a 'Yes' merely uttered to please, or worse, to avoid trouble." Mohandas Gandhi Quotes
: http://www.brainyquote.com/quotes/authors/m/mohandas_gandhi.html

--
http://www.freelists.org/webpage/oracle-l