Solution : https://service.sap.com/sap/support/notes/417835 (SAP Service marketplace login required)
Key words : 
optimizer -> global availability check -> product allocation -> maintain product allocation group, sap menu -> global atp -> environment -> allocations -> transfer connection, additional key words simsession performance update sales orderstransactions, indicator 'check planning area', function group /sapapo/atpq_index, prerequisites solution transactional simulation, product allocation group, availability check, bulk data transfer, product allocation groups
Related Notes : 
       
| 610704 | Composite SAP note: Performance of SD document update | 
| 609435 | Composite SAP note: Performance in backorder processing | 
| 517889 | Product allocations: SQL error -28530 when executing EXEC | 
| 512175 | Product allocations: SQL error -28530 when you execute EXEC | 
| 434474 | Allocations: SQL error 600 during execution of EXEC SQL | 
| 375193 | Backorder processing: Composite SAP note on posting | 
| 370601 | Composite SAP note: APO 3.0 and 3.1 performance | 
| 350804 | Message handler: Performance improvement |