You cannot compare DB2 performance with Oracle.
Also, an application developed against one particular RDBMS should NOT be deployed against with another RDBMS.
If the application commits after every row insert, then definitely Oracle is going to run slowly.
Finally, if you use 9i, You can increase _bump_highwater_mark_count to higher value in your test system. I think it defaults to 5. This parameter tells Oracle how many blocks should be allocated by advancing HW per freelist.
Also, consult with Oracle support before you change in PROD env.