[lessbergstein]

Perl would do it quite fast and it has the benefit of accessing posix primitives directly.

[gerikson]

A naive perl solution is really really slow compared to even the reference Java implementation. (I know, I've tried)

[lessbergstein]

That's strange, you should be able to stream the file right into a tiny perl executable at the same speed as the bottlenecking hardware. The kernel will take care of all the logistics. You're probably trying to do too much explicitly. Just use a pipe. Perl should be done before Jit completes.