The sleep command in your example puts this script rather firmly into the "Safe" category: sleeping is the precise method you use when you want something like this NOT to consume CPU resources. The sleep command does precisely what it implies: it sleeps in a very CPU friendly way.

A better test (minus the fork bomb mentioned below) would be:

$__++ while 1;
[download]

But even that is bland. Any decent operating system will run unhindered with this executing.

mr.nick ..