Sleep makes DoS attacks easier!

I think it may be better to remove this feature or give some explanation or warning. Because at first thought such random stutter seems a good idea, but then...

You can read a nice comment about DoS attacks using sleep on php.net:

"Unluckily, there is not much you can do against braindead criminals. Even if you block them on the IP layer, they can still fill the wire with datagrams :(
However, sleep() makes an attack a lot cheaper. If the target uses for example sleep(5); then the attacker can safely assume that one request will keep one process running for 5 seconds.
So, only a few dozen requests (w/ dropped connections), will safely run you into "MaxClients" and you will not be able to accept legitimate requests any more. So what, increase "MaxClients" then, I hear you say? The attacker can do this for hours, but you can't...
10MB of memory for a server process is not a unreasonable assumption. If your web server has 2GB of RAM then it will start thrashing after starting 200 processes. A 32 bit machine is out of virtual memory after 400. That can be achieved using a 14.4k modem..."