Solution : https://service.sap.com/sap/support/notes/63070 (SAP Service marketplace login required)
Key words : 
form userexit_xkomv_bewerten_init oder form userexit_xkomv_bewerten_end, scale base values, function module pricing_complete, suppress direct triggers, header condition screen, performance problems occur, group condition processing, source code corrections, total price determination, form userexit_new_pricing_vbap
Related Notes : 
       
| 536483 | BAPI SD: incomplete pricing | 
| 118743 | Collective note performance in SD | 
| 91830 | Performance in pricing |