Hi,
The only tuning you can do with dbload is tuning the number of rows before commit. Normally this is one large transaction, which is also the fastest. Of course can you do quite some tuning inside your databaseschema (indexes disabling for example) or in your configuration. But probably the best way to improve performance is using the high performance loader. I'll bet it will be really a lot faster.
Hope this helps you a bit,
Rob