Solution : https://service.sap.com/sap/support/notes/784503 (SAP Service marketplace login required)
Key words : 
sapbwnews bw support package 10 netweaver'04 stack 10, individual sql update statement runs, 10 content            import support package 19, 0b            import support package 25, 50            import support package 10, 1 content support package 19, unusually long time, work process- overview, database performance monitor, unfavorable access plan
Related Notes : 
       
| 825562 | DB6: Performance problems during data compression | 
| 791281 | DB6: SQL error "-104" during InfoCube/aggregate compression | 
| 763336 | SAPBWNews BW Support Package 10 NW '04 Stack 10 RIN | 
| 723261 | SAPBWNews BW 3.1 Content Support Package 19 | 
| 723254 | SAPBWNews BW 3.0B Support Package 25 | 
| 374502 | DB6: DB2 UDB - BW Performance - Overview of notes |