Hi,

I think I tried MCE::Map a few years ago, but will check it to be sure. I tried many methods so that is why I am convinced about the big hash, but I could be wrong of course, as there is much of Perl I don't know.
But small differences in speed will make a big difference because the script has to access the hash millions of time (I actually build 3 hashes), so some alternatives work fine at first sight, but on large datasets it slows down a lot.
Similar software (in C++ or python) usually need even more memory than mine (although they use a different graph based method so hard to compare)

(As an aside, have you profiled your code? I would think that Perl could load data from anywhere (file, database, whatever) faster than a shell call to an external analytical program would return ... or does your program not expect a response?)
Sorry I don't understand the question, is this about the system call? And I guess I didn't profile the code, as I don't know what that means :)

I think I tried this one (MCE::Shared::Hash) and it turned out too slow, but again I need to verify this, I will check If find the code, else I will try it.
Thanks