Yes, I know what virtual memory is, I'm a computer engineer and I work on operating systems. I'm just extremely impressed that they needed 1.5 GB of address space, for christ's sake.
Insert here some pithy comment about Apollo missions and Twitter, or whatever.
The reason I suspected that is grabbing 1.5 GB of virtual memory doesn't mean much. It just means you asked the OS to change its book-keeping to allow you to access that much. Applications and libraries that aggressively cache and prefetch routinely do that sort of thing.