php - Zend_View_Helper_Partial - performance measure

Question

I am trying to extend the zend partial helper to make it a little faster for my own needs. The code of how I do that is not important at this point.

I have created a unit test which acts weird and I can not understand the reason for it

this is the code:

    $garpTimeStart = microtime(true);
    for ($i = 0; $i < 999; $i++) {
        $this->_createOneGarpView();
    }
    $garpTimeTotal = microtime(true) - $garpTimeStart;

    $zendTimeStart = microtime(true);
    for ($i = 0; $i < 999; $i++) {
        $this->_createOneZendView();
    }
    $zendTimeTotal = microtime(true) - $zendTimeStart;

    $deltaPerformance = $zendTimeTotal - $garpTimeTotal;
    $this->assertTrue($deltaPerformance > 0);

ok, basically I create 1000 zendView objects and 1000 of my own garpView objects and I track the time for creating each of these.

Here comes the tricky part:

Simply by switching the order of the creation of the zend and garp views the test will fail. So, in other words, whichever I create first, will be created faster! (still, with a obvious difference in performance between the two)

So this in about 4 out of 5 times will fail

    $zendTimeStart = microtime(true);
    for ($i = 0; $i < 999; $i++) {
        $this->_createOneZendView();
    }
    $zendTimeTotal = microtime(true) - $zendTimeStart;

    $garpTimeStart = microtime(true);
    for ($i = 0; $i < 999; $i++) {
        $this->_createOneGarpView();
    }
    $garpTimeTotal = microtime(true) - $garpTimeStart;

    $deltaPerformance = $zendTimeTotal - $garpTimeTotal;
    $this->assertTrue($deltaPerformance > 0);

What am I missing? how can I create a more suitable environment to test this in?