How to improve the performance with CRMXIF_ORDER_SAVE

Hello CRM experts,

I have to upload 3 millions of records for Contract in CRM.Currently I have created the program with Parallel Jobs Processing and using FM CRMXIF_ORDER_SAVE to save the data.

Now for uploading of 2000 line items of 1 header in 1 Job system taking 1 hour to uploading and saved it succesfully.As we have to upload 3 millions records of Contract so it will take number of days.

When number of records will get increase in number of JOBS system will complete in numbers of hours.Is there any solution te reduce the time and data get saved successfully.

Please help me to reduce the timings to upload the data .

Thanks!!!