Solution : https://service.sap.com/sap/support/notes/558191 (SAP Service marketplace login required)
Key words : 
debugger -> goto -> system areas -> internal information -> itab-top25, terms query memory reason, s-dnnn memory containers, <g_thx_s> table appears, bw support packages, import support package 6, 0b support package 6, provide information, memory area, support package
Related Notes : 
       
| 563608 | Too much memory consumption in OLAP processor | 
| 558117 | Long OLAP runtime for special queries (COLLECT_S FORM) |