title: Elasticsearch client: speed up client creation
body: <p>I am developing integration tests with elasticsearch. At the beginning I instantiate the client like this:</p>
  
  <pre><code>Settings settings = Settings.EMPTY;
  Client client = new PreBuiltTransportClient(settings)
                  .addTransportAddress(new TransportAddress(InetAddress.getByName("localhost", "9300"));
  </code></pre>
  
  <p>The elasticsearch server is embedded into a docker container, with following environment variables:</p>
  
  <pre><code>- cluster.name=elasticsearch
  - "ES_JAVA_OPTS=-Xms512m -Xmx512m"
  - xpack.security.enabled=false
  - xpack.monitoring.enabled=false
  - xpack.graph.enabled=false
  - xpack.watcher.enabled=false
  </code></pre>
  
  <p>At each test run, it takes up to 20s just for client creation.</p>
  
  <p>Is there anyway to speed it up?
  Thx.</p>