The point about the speed in loops is, that the middle and the last expression are executed EVERY time it loops.
So you should try to take everything that doesn't change out of the loop.
Often you use a function to check the maximum of times it should loop. Like here:
<?php
for ($i = 0; $i <= somewhat_calcMax(); $i++) {
somewhat_doSomethingWith($i);
}
?>
Faster would be:
<?php
$maxI = somewhat_calcMax();
for ($i = 0; $i <= $maxI; $i++) {
somewhat_doSomethingWith($i);
}
?>
And here a little trick:
<?php
$maxI = somewhat_calcMax();
for ($i = 0; $i <= $maxI; somewhat_doSomethingWith($i++)) ;
?>
The $i gets changed after the copy for the function (post-increment).
