When inserting to a DB, the very most important thing is the number of transactions per second. If you try to run a transaction per insert, this will just "auger into the ground" performance wise. The DB will be limited by transactions per second. You can easily insert one million rows in a single transaction.

I have no experience with Oracle, but the basic principle I mentioned above is true for all SQL DB's.

Update: A DB transaction leaves the HD in a known state - no matter what happens during the transaction. This requires multiple writes and reads with associated rotational hard disk delays. A million row insert may not take much longer than a single row insert. That is because of all of this "book keeping" is related to number of transactions, not the amount of data or the number of rows.