Thanks for all the replies. They are very much appreciated!

What continues to be a mystery is why a procedure that has been running since 2005 for 20 minutes would increase to 11+ hours. (It appears to me that the optimizer is forcing a cursor operation.)

Even more confusing, is that the extended run time appeared on our development system whithout warning yesterday. Previously, the process was running 20 minutes, now 11+ hours.

What would cause this kind of behavior?