Performance of while(true) loop

Hey list, I have a php cli script that listens on a UDP socket and, when data is sent to the socket, the script inserts it into a database. I'm using the real BSD socket functions, not fsock. The script runs socket_create(), then socket_bind(). Then it starts a while(TRUE) loop. Within the loop, it runs socket_recvfrom(). I have it running 24/7 inside a screen window. I'm curious as to the cpu/memory/etc usage of a while(true) loop. The top command shows that the process is in the sbwait state (the OS is FreeBSD). I'm contemplating adding a usleep or even a sleep inside to loop. Would this be beneficial? I'm not too sure of how the internals of PHP work in terms of loops and such. Thanks.