cLIeNUX false is about as fast as you can write a C program. Here's how the command compares to the built-in....
:; cLIeNUX /dev/tty2 13:53:38 /command :;time /.bi/false real 0m0.037s user 0m0.000s sys 0m0.020s :; cLIeNUX /dev/tty2 13:53:45 /command :;time false real 0m0.001s user 0m0.010s sys 0m0.000s :; cLIeNUX /dev/tty2 13:53:52 /command :;The builtin is 37 times faster than a command that does almost nothing.