Solution : https://service.sap.com/sap/support/notes/1230118 (SAP Service marketplace login required)
Key words : 
include lbbp_pddepf04 form pddep_maintain_all, symptom low system performance, srm-ebp-con, document check reason, attachedadvance correction manually, system time, large number, large contracts, time consuming, terms contract
Related Notes : 
       
| 1227042 | Performance improvement in contract for document check | 
| 1169088 | SRM 6.0 Performance Guide |