BAPI_MOSRVAPS_SAVEMULTI3 Taking longer time to complete

I am calling this bapi passing 100k records in the background job and it takes more than 5hrs to complete. Is there any way this run time can be reduced.

I cannot slice the file as I need to create the master schedule either all or none.

also I tried 'In Background' while calling the BAPI using the qRFC but this transaction async will not return the result back us.

So my question to here is how do we get the return data from the method of calling the bapi.

Any help/suggestion is appreciated.