Solution : https://service.sap.com/sap/support/notes/533425 (SAP Service marketplace login required)
Key words : 
symptom long runtimes occur, attached source code corrections, terms bp_exchange_r3_to_crm reason, initial download, object customer_main, program error, solution implement, extraction, prerequisites
Related Notes : 
       
| 537486 | Composite SAP note:perfrmnce problms during initial download |