How to reduce the average time for X records for PO Import Program

Hi All

We are building a new interface for inbound Purchase Orders with Oracle EBS R12. We are using standard interface route for the data load from a staging table. We are using atleast 7 DFF in header table and 12+ DFF in line tables. Currently, for 20K PO Headers and corresponding 240K PO lines, it is taking 15+ hours for the standard import program.

Our data volume on a daily basis is quite high as we are a big manufacturing company. Is the above timing is average or there is a benchmark timing available for X number of records processed through standard PO import program? How can we reduce the import program processing timing? Any pointers will be appreciated.