myArray = [];

for "_i" from 0 to 1000000 do {
    myArray set [count myArray, _i];
};

hint "DONE POPULATING ARRAY";

myFunction = {
    [] spawn {
        _startTime = diag_tickTime;

        /*
        {
            _tmp = _x;
        } forEach myArray;
        */

        /*
        {
            _tmp = _x;
        } count myArray;
        */

        for "_i" from 0 to (count myArray - 1) do {
            _tmp = myArray select _i;
        };

        _diff = diag_tickTime - _startTime;
        diag_log (str (_diff));
    }
}

/*
            unscheduled (blocking engine)       scheduled (not blocking engine)
forEach     1.66449                             5.379515
count       1.2985075                           4.25299
for         1.95398                             6.209015
*/