set_time_limit and print problem

[Coba]

I've experienced many problems with set_time_limit(). I am trying to limit execution time of included script and no solution still. Included script is opening url with fopen and parse it.

this code runs forever:
set_time_limit(5);
while(1) {
print time();
}

but this is ok (exits after 5 secs):
set_time_limit(5);
while(1) {
}

what is wrong here? am i missing something?

[Coba]

i played some more with this:
set_time_limit(1);

while(1) {
}
//exits after 1 sec

while(1) {
print time()."\n";
}
//exits after 1 min 15 secs

while(1) {
$a=count("heh");
print "$a";
}
//exits after 1 min 45 sec
// warning says that 1 second limit is reached !!

so, is there any other solution to really limit time for script?