I'm just now noticing this, from your test: $ gcc threads.c $ time ./a.out real 0m10.097s user 0m0.035s sys 0m0.239s $ gcc process.c

I'm just now noticing this, from your test: $ gcc threads.c $ time ./a.out real 0m10.097s user 0m0.035s sys 0m0.239s $ gcc process.c $ time ./a.out real 0m10.168s user 0m0.579s sys 0m0.347s You were pleasantly surprised by your own test showing an order of magnitude speed gain in user space by using threads?