Did you ever found an answer for this?
I am on a server double your size, we got 512 GB ram and 64 CPU's
I noticed the same behavior as you did in one of my qvw:s
It was loading huge amount of data, and it went fairly quick, in 3h45min it had loaded 4 115 747 570 lines and was using ~256 GB ram, and then it just seemed to halt.
It did not crash, and did not exit, the Script Execution Progress window was still open and the Elapsed time was ticking on, it was runing over the weekend, so it in fact ticked on for 48 hrs, but nothing happened.