Возможна ли оптимизация

<?php
 
class Item {
    public $name = 'Battle Ship';
    public $defence = 5000;
    public $attack = 150;
}
 
$shipsA = [];
 
for($i = 0; $i < 3000000; $i++) {
    $shipsA[] = new Item();
}
 
echo 'init A complete...' . PHP_EOL;
 
$shipsB = [];
 
for($i = 0; $i < 1000000; $i++) {
    $shipsB[] = new Item();
}
 
echo 'init B complete...' . PHP_EOL;
 
$rounds = 10;
 
// start
 
$tmpA = $shipsA;
$tmpB = $shipsB;
 
while($rounds > 0 && !empty($shipsA) && !empty($shipsB)) {
 
    foreach ($shipsA as $ship) {
        if (empty($tmpB)) { break; };
 
        // select random B sheep
        $index = array_rand($tmpB);
        // Update data
        $tmpB[$index]->defence-=$ship->attack;
        // clear empty
        if ($tmpB[$index]->defence <= 0) {
            array_splice($tmpB, $index, 1);
        }
    }
 
    foreach ($shipsB as $ship) {
        if (empty($tmpA)) { break; };
 
        // select random B sheep
        $index = array_rand($tmpA);
        // Update data
        $tmpA[$index]->defence-=$ship->attack;
        // clear empty
        if ($tmpA[$index]->defence <= 0) {
            array_splice($tmpA, $index, 1);
        }
    }
 
    $shipsA = $tmpA;
    $shipsB = $tmpB;
 
// end round
    $rounds--;
    echo "Round: $rounds\n";
}
 
echo "-----\n";
echo "ShipsA: " . count($shipsA) . "\n";
echo "ShipsB: " . count($shipsB) . "\n";

$index = mt_rand(0, count($array)-1);

$tmpB[$index] = $tmpB[count($tmpB)-1];
unset($tmpB[count($tmpB)-1]);