>I'm trying to delete 10 million records from a 50 million record table in chunks of about 20,000 records, then a COMMIT.
>
>The process is very slow, about 100,000 per hour. All triggers, and constraints on this table are disabled?
>
>What am I missing?

What does your DELETE SQL look like? Do you have an index on filtered columns in the WHERE clause? That many records will still take some time. Also, as you delete, indexes are being updated. You could drop indexes that are not involved in your WHERE clause. Maybe dropping all indexes will help as well.