Question

I am looking for a fastest(performance) way to cycle/alternative 2 values inside of a foreach loop. Exactly the same as the smarty works: http://www.smarty.net/docsv2/en/language.function.cycle

Answer 1

$cycle = array('value1', 'value2');
$i = 0;

foreach (...) {
    $cycle[$i] // current cycle value
    ...
    $i = 1 - $i; // here be cycling
}

P.S. And don’t think you should be very concerned about performance in this case.