Solution : https://service.sap.com/sap/support/notes/129511 (SAP Service marketplace login required)
Key words : 
additional key words l1 l3 statistics nffz case-, l1/l3 statistics, symptom performance problems occur, -case assignment rnsl102 rnsl302, reading table nffz, 5th change regulation, open-sql statements, table nffz, -case assignment, 2 separate statements
Related Notes : 
       
| 119281 | IS-H: Current collective note on important errors in 4.02A | 
| 114716 | Performance problems Oracle 8.0.4/all entries | 
| 101101 | IS-H:Upd.collective note, important errors in 4.01A | 
| 99311 | Current patch set 8.0.4.X |