Solution : https://service.sap.com/sap/support/notes/387964 (SAP Service marketplace login required)
Key words : 
key fieldsoltpsource = ' 'param_name = 'notsselect', additional key words 0co_om_cca_9, 0co_om_nwa_2 performance problems occur, source code corrections attached, delta updateparam_value = 'x' access, full update runs faster, delta init mode, delta init update, delta init, full update
Related Notes : 
       
| 578417 | BCT-CO: CO-OM delta DataSources: Executing the DeltaInit | 
| 567747 | Composite note BW 3.x performance: Extraction & loading | 
| 549552 | CO line item extractors: performance | 
| 457317 | BCT-CO Delta DataSources: Missing data with NOTSSELECT = X | 
| 432715 | BCT-CO Delta DataSources: No data for delta init run | 
| 412902 | BCT-CO delta DataSources: Not all data extracted | 
| 399123 | CO delta extractors: Error in Note 387964 | 
| 398041 | INFO: CO-OM/IM-Content (BW) | 
| 382329 | Delta extractors CO: Poor performance |