<code>$time = microtime(true);
for ($i = 0; $i <= 3; $i++) {
    for ($i2 = 0; $i2 <= 1000; $i2++) {
        $res = $modx->getObject('modResource', 1);
    }
}

echo 'Time: '.(microtime(true) - $time).' s
';
echo 'Memory: '.round((memory_get_peak_usage(true) / 1024 / 1024),2).' Mb';
die;</code>

Time: 9.5783779621124 s Memory: 7.25 Mb
Time: 9.4243011474609 s Memory: 13.25 Mb
Time: 9.3328008651733 s Memory: 8.5 Mb