如何优化此代码段以更快地执行并占用更小的空间？

We have a small script that uses memcache to track concurrent sessions, with the client making a new request every 10-seconds to "renew" its session and also get the latest count of users online.

$session    = $_GET['session'];
$streamid   = $_GET['streamid'];

if(!is_null($session) && !is_null($streamid)) {
    $memcache = new Memcache;
    $memcache->connect('localhost', 11211);

    $data   = $memcache->get($streamid);

    if($data === false) {
        $data   = array($session => time()+10);

        $memcache->add($streamid,$data,0,10);
    } else {
        $now            = time();
        $streamCount    = count($data);

        for($i=0;$i<$streamCount;$i++) {
            if($data[$i] > $now) {    
                    unset($data[$i]);
            }
        }

        $data[$session] = time()+10;
    }

    echo count($data);
} else {
    echo 'no session or stream specified';
}

Have you tried running this yet? Do you need to optimize it? Maybe it works like how you want it right now. It seems like a better solution would be to decouple it and write it as clean as possible. Put timers around calls and if you see something being slow then try to fix that code. Don't optimize if you don't need to.