diff --git a/sail/pom.xml b/sail/pom.xml
index 295210c52..c1d7d811f 100644
--- a/sail/pom.xml
+++ b/sail/pom.xml
@@ -44,6 +44,11 @@
             <artifactId>elasticsearch-java</artifactId>
             <version>${elasticsearch.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.elasticsearch.client</groupId>
+            <artifactId>elasticsearch-rest-client-sniffer</artifactId>
+            <version>${elasticsearch.version}</version>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
diff --git a/sail/src/main/java/com/msd/gin/halyard/sail/ElasticSettings.java b/sail/src/main/java/com/msd/gin/halyard/sail/ElasticSettings.java
index 341eec536..17bf2bca0 100644
--- a/sail/src/main/java/com/msd/gin/halyard/sail/ElasticSettings.java
+++ b/sail/src/main/java/com/msd/gin/halyard/sail/ElasticSettings.java
@@ -23,15 +23,24 @@
 import org.apache.http.client.CredentialsProvider;
 import org.apache.http.impl.client.BasicCredentialsProvider;
 import org.apache.http.impl.nio.client.HttpAsyncClientBuilder;
+import org.apache.http.impl.nio.reactor.IOReactorConfig;
 import org.elasticsearch.client.RestClient;
 import org.elasticsearch.client.RestClientBuilder;
 import org.elasticsearch.client.RestClientBuilder.HttpClientConfigCallback;
+import org.elasticsearch.client.sniff.ElasticsearchNodesSniffer;
+import org.elasticsearch.client.sniff.NodesSniffer;
+import org.elasticsearch.client.sniff.Sniffer;
 
+import co.elastic.clients.json.JsonpMapper;
 import co.elastic.clients.json.jackson.JacksonJsonpMapper;
 import co.elastic.clients.transport.ElasticsearchTransport;
 import co.elastic.clients.transport.rest_client.RestClientTransport;
 
 public final class ElasticSettings {
+	private static final String USER = "es.net.http.auth.user";
+	private static final String PASS = "es.net.http.auth.pass";
+	private static final String IO_THREADS = "halyard.es.ioThreads";
+
 	String protocol;
 	String host;
 	int port;
@@ -39,6 +48,7 @@ public final class ElasticSettings {
 	String password;
 	String indexName;
 	SSLSettings sslSettings;
+	int ioThreads;
 
 	public String getProtocol() {
 		return protocol;
@@ -89,44 +99,50 @@ public static ElasticSettings from(String esIndexUrl, Configuration conf) {
 			throw new IllegalArgumentException(e);
 		}
 		if (merged.username == null) {
-			merged.username = conf.get("es.net.http.auth.user");
+			merged.username = conf.get(USER);
 		}
 		if (merged.password == null) {
-			merged.password = conf.get("es.net.http.auth.pass");
+			merged.password = conf.get(PASS);
 		}
 		if ("https".equals(merged.protocol)) {
 			merged.sslSettings = SSLSettings.from(conf);
 		}
+		merged.ioThreads = conf.getInt(IO_THREADS, 0);
 		return merged;
 	}
 
 	public static ElasticSettings merge(Configuration conf, ElasticSettings defaults) {
-		ElasticSettings merged;
+		ElasticSettings urlSettings;
 		String esIndexUrl = conf.get(HBaseSail.ELASTIC_INDEX_URL);
 		if (esIndexUrl != null) {
 			try {
-				merged = from(new URL(esIndexUrl));
+				urlSettings = from(new URL(esIndexUrl));
 			} catch (MalformedURLException e) {
 				throw new IllegalArgumentException(e);
 			}
 		} else if (defaults != null) {
-			merged = new ElasticSettings();
-			merged.protocol = defaults.protocol;
-			merged.host = defaults.host;
-			merged.port = defaults.port;
-			merged.indexName = defaults.indexName;
+			urlSettings = new ElasticSettings();
+			urlSettings.protocol = defaults.protocol;
+			urlSettings.host = defaults.host;
+			urlSettings.port = defaults.port;
+			urlSettings.indexName = defaults.indexName;
 		} else {
 			return null;
 		}
-		if (merged.username == null) {
-			merged.username = conf.get("es.net.http.auth.user", defaults != null ? defaults.username : null);
+		if (urlSettings.username == null) {
+			urlSettings.username = defaults.username;
 		}
-		if (merged.password == null) {
-			merged.password = conf.get("es.net.http.auth.pass", defaults != null ? defaults.password : null);
+		if (urlSettings.password == null) {
+			urlSettings.password = defaults.password;
 		}
+
+		ElasticSettings merged = urlSettings;
+		merged.username = conf.get(USER, urlSettings.username);
+		merged.password = conf.get(PASS, urlSettings.password);
 		if ("https".equals(merged.protocol)) {
 			merged.sslSettings = SSLSettings.merge(conf, defaults != null ? defaults.sslSettings : null);
 		}
+		merged.ioThreads = conf.getInt(IO_THREADS, defaults != null ? defaults.ioThreads : 0);
 		return merged;
 	}
 
@@ -154,10 +170,44 @@ public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpCli
 				if (sslContext != null) {
 					httpClientBuilder.setSSLContext(sslContext);
 				}
+				if (ioThreads > 0) {
+					httpClientBuilder.setDefaultIOReactorConfig(IOReactorConfig.custom().setIoThreadCount(ioThreads).build());
+				}
 				return httpClientBuilder;
 			}
 		});
 		RestClient restClient = restClientBuilder.build();
-		return new RestClientTransport(restClient, new JacksonJsonpMapper());
+		ElasticsearchNodesSniffer.Scheme snifferScheme;
+		switch (protocol) {
+			case "http":
+				snifferScheme = ElasticsearchNodesSniffer.Scheme.HTTP;
+				break;
+			case "https":
+				snifferScheme = ElasticsearchNodesSniffer.Scheme.HTTPS;
+				break;
+			default:
+				throw new AssertionError("Unsupported scheme: " + protocol);
+		}
+		NodesSniffer nodesSniffer = new ElasticsearchNodesSniffer(restClient, ElasticsearchNodesSniffer.DEFAULT_SNIFF_REQUEST_TIMEOUT, snifferScheme);
+		Sniffer sniffer = Sniffer.builder(restClient).setNodesSniffer(nodesSniffer).build();
+		return new RestClientTransportWithSniffer(restClient, new JacksonJsonpMapper(), sniffer);
+	}
+
+	private static final class RestClientTransportWithSniffer extends RestClientTransport {
+		private final Sniffer sniffer;
+
+		public RestClientTransportWithSniffer(RestClient restClient, JsonpMapper mapper, Sniffer sniffer) {
+			super(restClient, mapper);
+			this.sniffer = sniffer;
+		}
+
+		@Override
+		public void close() throws IOException {
+			try {
+				sniffer.close();
+			} finally {
+				super.close();
+			}
+		}
 	}
 }
\ No newline at end of file
diff --git a/webapps/pom.xml b/webapps/pom.xml
index 10f94dddf..e54e19064 100644
--- a/webapps/pom.xml
+++ b/webapps/pom.xml
@@ -158,6 +158,11 @@
 									<artifactId>elasticsearch-rest-client</artifactId>
 									<version>${elasticsearch.version}</version>
 								</artifactItem>
+								<artifactItem>
+									<groupId>org.elasticsearch.client</groupId>
+									<artifactId>elasticsearch-rest-client-sniffer</artifactId>
+									<version>${elasticsearch.version}</version>
+								</artifactItem>
 								<artifactItem>
 									<groupId>org.apache.httpcomponents</groupId>
 									<artifactId>httpasyncclient</artifactId>