### Is there an existing issue for this?

- [X] I have searched the existing issues

### Current Behavior

It seems like whenever I open a connection to `localhost:4566` (4566 being exposed from the localstack container), for the next ~1 second any HTTP calls will have delayed responses. If I open 10 connections, the delay will be 10 seconds.

### Expected Behavior

Multiple connections can be opened and don't impact other requests until a certain connection limit.

### How are you starting LocalStack?

With a `docker run` command

### Steps To Reproduce

1. run localstack: `docker run --rm -it -p 4566:4566 --name ls localstack/localstack:0.14.0` - I managed to reproduce it with versions as old as 0.12.0
2. run something like this to see how long curls take inside the container: 

```bash
docker exec -it ls /bin/bash

# inside the container:
while true; do time curl localhost:4566; sleep 0.1; done
```

3. open connections with telnet:

```
telnet localhost 4566
```

4. observe extended response times in the curl loop. For me it's ~1s extra per open connection (I'm simulating opening more connections with a JVM application opening sockets as I request).

### Environment

```markdown
- OS: macOS / ubuntu, tried both x86 and arm64 macs, and an arm64 linux
- LocalStack: 0.12.0, 0.13.1, 0.14.0
```


### Anything else?

This surfaces itself as extremely slow responses whenever you have e.g. a JVM application that keeps a cached connection pool. Even 10 connections in a pool are enough to cause consistent delays every couple seconds (which I think is after the connections are closed due to the defaults on my client), under no additional traffic targeting localstack.
client_address=request.remote_addr,
            server_address=parsed_url.netloc,
        )
    ssl_creds = (None, None)
    if use_ssl:
        install_predefined_cert_if_available()
        _, cert_file_name, key_file_name = GenericProxy.create_ssl_cert(serial_number=port)
        ssl_creds = (cert_file_name, key_file_name)
    result = http2_server.run_server(
        port,
        bind_addresses=bind_addresses,
        handler=handler,
        asynchronous=asynchronous,
        ssl_creds=ssl_creds,
        max_content_length=max_content_length,
        send_timeout=send_timeout,
    )
    if asynchronous and check_port:
        wait_for_port_open(port, sleep_time=0.2, retries=12)
    return result
def install_predefined_cert_if_available():
    try:
        from localstack_ext.bootstrap import install
        if config.SKIP_SSL_CERT_DOWNLOAD:
            LOG.debug("Skipping download of local SSL cert, as SKIP_SSL_CERT_DOWNLOAD=1")
            return
        install.setup_ssl_cert()
    except Exception:
        pass
def serve_flask_app(app, port, host=None, cors=True, asynchronous=False):