Solution : https://service.sap.com/sap/support/notes/174606 (SAP Service marketplace login required)
Key words : 
require long runtimes, /3 hr support packages, deactivated part exists, routine write_statistics advises, hr support package 7, start zpu40acl automatically, -digit sequence numberso, automatic parallel processing, manual parallel processing------------------------, parallel processing means
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| 156956 | Conversion of payroll results for Rel. 4.0 |