Sure, but who calls your main()? Usually when you're in a shell, which in turn calls exec and copies over some data. If you're that worried about performance a

Sure, but who calls your main()? Usually when you're in a shell, which in turn calls exec and copies over some data. If you're that worried about performance about a few string allocations, you shouldn't be passing around strings anyway, shell or not.. And simply call functions from the same process and use for example the file descriptors you already have. You could also just simply pass a binary blob (messagepack) as one of the arguments, if that's your thing.