when I try to upload a large file, localstack basically freezes (and eventually times out).  
But if the file is all `1` bytes it succeeds.

succeeds:
```bash
aws s3 --endpoint-url=http://localhost:4572 mb s3://testbucket
python -c "print '\x01'*10000000" > testfile
echo $(ls -ahl | grep testfile)
aws s3 --endpoint-url=http://localhost:4572 cp testfile s3://testbucket/testfile
```

fails:
```bash
aws s3 --endpoint-url=http://localhost:4572 mb s3://testbucket
python -c "print 'a'*10000000" > testfile
echo $(ls -ahl | grep testfile)
aws s3 --endpoint-url=http://localhost:4572 cp testfile s3://testbucket/testfile
```
so, for me, both the file content and its size determine if this triggers or not. 
I'm using the latest version `0.9.5`
self.assertEqual(response.status_code, 200)
        self.assertEqual(response.text, 'This is the error document')
        
        self.s3_client.delete_object(Bucket=bucket_name, Key='error.html')
        self.s3_client.delete_bucket(Bucket=bucket_name)
        
        bucket_name = 'test-bucket-%s' % short_uid()
        self.s3_client.create_bucket(Bucket=bucket_name)
        self.s3_client.put_bucket_website(
            Bucket=bucket_name,
            WebsiteConfiguration={'IndexDocument': {'Suffix': 'index.html'}}
        )
        url = self.s3_client.generate_presigned_url(
            'get_object', Params={'Bucket': bucket_name, 'Key': 'nonexistent'}
        )
        response = requests.get(url, verify=False)
        self.assertEqual(response.status_code, 404)
        
        self.s3_client.delete_bucket(Bucket=bucket_name)
        
        bucket_name = 'test-bucket-%s' % short_uid()
        self.s3_client.create_bucket(Bucket=bucket_name)
        url = self.s3_client.generate_presigned_url(
            'get_object', Params={'Bucket': bucket_name, 'Key': 'nonexistent'}
        )
        response = requests.get(url, verify=False)
        self.assertEqual(response.status_code, 404)
        
        self.s3_client.delete_bucket(Bucket=bucket_name)
    def test_s3_event_notification_with_sqs(self):