[dagw]

Most of that time is spent executing poorly crafted Oracle SQL queries

Start by looking here. As much as we love to bag on Oracle, it is at its core a really fast and capable database. I don't know what you are doing, but doing anything with only 81M records shouldn't take 17 hours. Profile you SQL, rewrite it, if necessary bring in a Oracle SQL expert, and I'm pretty sure you will find some easy wins just here. Perhaps even enough to solve your performance problems. If you're doing relational database type work, it's hard to beat a relational database.