[dooglius]

One thing worth pointing out is that Linux makes it pretty difficult for userspace to access uninitialized memory; the MAP_UNINITIALIZED flag for mmap has to be specifically configured but generally isn't, so the memory does get zeroed at some point. Best you can hope for is that your heap allocator re-uses some un-munmapped memory. The kernel will zero pages on-demand, which helps, but you're still paying a cost for that zeroing.