Is the 6GB usage you're seeing for the entire system or solely for the qv.exe process? If you're running the 32-bit version of QlikView, even on a 64-bit OS any given process is limited to 4GB. This assumes you're reloading in QlikView desktop, not QVS/Publisher (although the same rule would apply; it would just be a qvb.exe process instead.)
Outside of that, if the single process isn't exceeding 6GB I would presume that it doesn't need anything beyond that.
