Solution : https://service.sap.com/sap/support/notes/145291 (SAP Service marketplace login required)
Key words : 
archiving class workitem takes extremely long, standard deletion function module sww_wi_delete, additional key words archiving, general function module permits, general deletion program rswwwide, function module sww_wi_delete, archiving object workitem, function group swwx, deletion program rswwarcd, symptom deleting data
Related Notes : 
       
| 737696 | Add. info on upgrade to SAP R/3 Enterprise 4.70 Ext. 2 SR1 | 
| 637683 | Add info about upgrade to SAP R/3 Enterprise Core 4.70 Ext 2 | 
| 587896 | Add. info on upgrade to SAP R/3 Enterprise Core 4.70 SR1 | 
| 573656 | Collective note relating to Archiving in workflow | 
| 420371 | Add. info on upgrading to Basis 4.6C SR2 (NDI upgrade) | 
| 390062 | Additional information about upgrading to 4.6C SR2 | 
| 329622 | Additions: Upgrading to Basis 4.6C SR1 (NDI upgrade) | 
| 327285 | Additions to upgrade to 4.6C SR1 | 
| 304597 | Additions to upgrade to Release 4.6C FCS | 
| 192949 | Additional info for upgrade to 4.6C | 
| 179373 | Additional info for upgrade to Rel.4.6B | 
| 155674 | Additions upgrade to Release 4.6A | 
| 117191 | Work item log is not deleted from archiving | 
| 49545 | Deleting unnecessary work items |