Ratchet benchmark
Hi, try to make ratchet benchmark http server and doing next:

```php
use Ratchet\Http\HttpServerInterface;
use Ratchet\ConnectionInterface;
use Psr\Http\Message\RequestInterface;

class Server implements HttpServerInterface
{
    public function onOpen(ConnectionInterface $conn, RequestInterface $request = null) {
        $conn->send("HTTP/1.1 200 OK\r\n");
        $conn->send("Content-type: text/plain\r\n");
        $conn->send("\r\n");
        $conn->send("test");
        $conn->close();
    }

    public function onMessage(ConnectionInterface $from, $msg) {}

    public function onClose(ConnectionInterface $conn) {}

    public function onError(ConnectionInterface $conn, \Exception $e) {}
}

use Ratchet\Http\HttpServer;
use Ratchet\Server\IoServer;

$server = IoServer::factory(
    new HttpServer(new Server()), 9057
);

$server->run();
```

**But result with Apache Benchmark is no so good:**

```
ab -c 10 -n 1000000 http://site.ll:9057/?user=tester01
This is ApacheBench, Version 2.3 <$Revision: 1706008 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking curex.ll (be patient)
Completed 100000 requests
Completed 200000 requests
Completed 300000 requests
Completed 400000 requests
Completed 500000 requests
Completed 600000 requests
Completed 700000 requests
Completed 800000 requests
Completed 900000 requests
Completed 1000000 requests
Finished 1000000 requests

Server Software:        
Server Hostname:        curex.ll
Server Port:            9057

Document Path:          /?user=tester01
Document Length:        4 bytes

Concurrency Level:      10
Time taken for tests:   465.773 seconds
Complete requests:      1000000
Failed requests:        0
Total transferred:      49000000 bytes
HTML transferred:       4000000 bytes
Requests per second:    2146.97 [#/sec] (mean)
Time per request:       4.658 [ms] (mean)
Time per request:       0.466 [ms] (mean, across all concurrent requests)
Transfer rate:          102.74 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.0      0       8
Processing:     0    5   0.4      5      16
Waiting:        0    5   0.4      5      16
Total:          1    5   0.4      5      16

Percentage of the requests served within a certain time (ms)
  50%      5
  66%      5
  75%      5
  80%      5
  90%      5
  95%      5
  98%      6
  99%      6
 100%     16 (longest request)
```

`Time taken for tests:   465.773 seconds`

**What I am doing wrong?**