Solution : https://service.sap.com/sap/support/notes/650188 (SAP Service marketplace login required)
Key words :
de-activate update processes, availability check grows, processed order items, availability check takes, table /sapapo/brequire, terms performance reason, source code corrections, problems occur, memory consumption, quadratic progression
Related Notes :
| 609435 | Composite SAP note: Performance in backorder processing |