### 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.
headers[ACL_ORIGIN] = (
            request_headers["origin"]
            if request_headers.get("origin") and not config.DISABLE_CORS_CHECKS
            else "*"
        )
    if ACL_METHODS not in headers:
        headers[ACL_METHODS] = ",".join(CORS_ALLOWED_METHODS)
    if ACL_ALLOW_HEADERS not in headers:
        requested_headers = headers.get(ACL_REQUEST_HEADERS, "")
        requested_headers = re.split(r"[,\s]+", requested_headers) + CORS_ALLOWED_HEADERS
        headers[ACL_ALLOW_HEADERS] = ",".join([h for h in requested_headers if h])
    if ACL_EXPOSE_HEADERS not in headers:
        headers[ACL_EXPOSE_HEADERS] = ",".join(CORS_EXPOSE_HEADERS)
    for header in ALLOWED_CORS_RESPONSE_HEADERS:
        if headers.get(header) == "":
            del headers[header]
def http_exception_to_response(e: HTTPException):
    """Convert a werkzeug HTTP exception to a requests.Response object"""
    response = Response()
    response.status_code = e.code
    response.headers.update(dict(e.get_headers()))
    body = e.get_body()
    response.headers["Content-Length"] = str(len(str(body or "")))
    response._content = body
    return response
def cors_error_response():
    response = Response()
    response.status_code = 403
    return response
def _is_in_allowed_origins(allowed_origins, origin):