[Ellipsis753]

Interestingly, because your program runs on Linux and is run 5 times, Linux will almost certainly cache the 12gb file to RAM on the first invocation.

This means that future invocations don't have to load the file from disk. This also makes it pretty critical that your program doesn't use more than 16gb of ram itself (out of the server's 32gb) or it'll push the file out of cache making future invocations of your program slower.