Solution : https://service.sap.com/sap/support/notes/499906 (SAP Service marketplace login required)
Key words : 
bp inbound processing, transfer large datasets, terms bp_exchange_r3_to_crmbp_exchange_frgn_to_crm reason, source code corrections, business partner, system reads, performance losses, initial download, data exchange, solution implement
Related Notes : 
       
| 537486 | Composite SAP note:perfrmnce problms during initial download |