diff --git a/helix-core/src/main/java/org/apache/helix/util/ZKClientPool.java b/helix-core/src/main/java/org/apache/helix/util/ZKClientPool.java
index e484ee353b..e666358b4b 100644
--- a/helix-core/src/main/java/org/apache/helix/util/ZKClientPool.java
+++ b/helix-core/src/main/java/org/apache/helix/util/ZKClientPool.java
@@ -28,7 +28,7 @@
 
 public class ZKClientPool {
   static final Map<String, ZkClient> _zkClientMap = new ConcurrentHashMap<>();
-  static final int DEFAULT_SESSION_TIMEOUT = 30 * 1000;
+  static final int DEFAULT_SESSION_TIMEOUT = 3 * 1000;
 
   public static ZkClient getZkClient(String zkServer) {
     // happy path that we cache the zkclient and it's still connected
diff --git a/helix-core/src/test/java/org/apache/helix/TestHelper.java b/helix-core/src/test/java/org/apache/helix/TestHelper.java
index 25ab2f96bf..da3834c55b 100644
--- a/helix-core/src/test/java/org/apache/helix/TestHelper.java
+++ b/helix-core/src/test/java/org/apache/helix/TestHelper.java
@@ -124,7 +124,7 @@ static public ZkServer startZkServer(final String zkAddress, final List<String>
       FileUtils.deleteDirectory(new File(dataDir));
       FileUtils.deleteDirectory(new File(logDir));
     }
-    ZKClientPool.reset();
+//    ZKClientPool.reset();
 
     IDefaultNameSpace defaultNameSpace = new IDefaultNameSpace() {
       @Override
@@ -145,7 +145,7 @@ public void createDefaultNameSpace(ZkClient zkClient) {
 
     int port = Integer.parseInt(zkAddress.substring(zkAddress.lastIndexOf(':') + 1));
     ZkServer zkServer = new ZkServer(dataDir, logDir, defaultNameSpace, port);
-    zkServer.start();
+    timeIt(() -> zkServer.start());
 
     return zkServer;
   }
diff --git a/helix-core/src/test/java/org/apache/helix/integration/TestStateTransitionCancellation.java b/helix-core/src/test/java/org/apache/helix/integration/TestStateTransitionCancellation.java
index 0e9b70ed1b..54b9369ea1 100644
--- a/helix-core/src/test/java/org/apache/helix/integration/TestStateTransitionCancellation.java
+++ b/helix-core/src/test/java/org/apache/helix/integration/TestStateTransitionCancellation.java
@@ -91,9 +91,6 @@ public void testCancellationWhenDisableResource() throws InterruptedException {
     clusterConfig.stateTransitionCancelEnabled(true);
     _configAccessor.setClusterConfig(CLUSTER_NAME, clusterConfig);
 
-    // Wait for assignment done
-    Thread.sleep(2000);
-
     // Disable the resource
     _gSetupTool.getClusterManagementTool().enableResource(CLUSTER_NAME,
         WorkflowGenerator.DEFAULT_TGT_DB, false);
@@ -160,8 +157,6 @@ public void testRebalancingCauseCancellation() throws InterruptedException {
     MockParticipantManager[] newParticipants = new MockParticipantManager[numNodesToStart];
     registerParticipants(newParticipants, numNodesToStart, _startPort + _numNodes, 1000, -3000000L);
 
-    // Wait for pipeline reaching final stage
-    Thread.sleep(2000L);
     int numOfMasters = 0;
     ExternalView externalView = _gSetupTool.getClusterManagementTool()
         .getResourceExternalView(CLUSTER_NAME, WorkflowGenerator.DEFAULT_TGT_DB);
@@ -291,10 +286,6 @@ public Task createNewTask(TaskCallbackContext context) {
       stateMach.registerStateModelFactory(MASTER_SLAVE_STATE_MODEL, delayFactory);
 
       participants[i].syncStart();
-
-      if (sleepTime > 0) {
-        Thread.sleep(sleepTime);
-      }
     }
   }
 }
diff --git a/helix-core/src/test/java/org/apache/helix/integration/TestZkConnectionLost.java b/helix-core/src/test/java/org/apache/helix/integration/TestZkConnectionLost.java
index 6b8d9e8a59..d872a73fba 100644
--- a/helix-core/src/test/java/org/apache/helix/integration/TestZkConnectionLost.java
+++ b/helix-core/src/test/java/org/apache/helix/integration/TestZkConnectionLost.java
@@ -225,10 +225,8 @@ private void restartZkServer() throws ExecutionException, InterruptedException {
     for (int i = 0; i < 4; i++) {
       Executors.newSingleThreadExecutor().submit(() -> {
         try {
-          Thread.sleep(300);
           LOG.info(System.currentTimeMillis() + ": Shutdown ZK server.");
           TestHelper.stopZkServer(_zkServerRef.get());
-          Thread.sleep(300);
           LOG.info("Restart ZK server");
           _zkServerRef.set(TestHelper.startZkServer(_zkAddr, null, false));
         } catch (Exception e) {
diff --git a/helix-core/src/test/java/org/apache/helix/integration/controller/TestControllerLeadershipChange.java b/helix-core/src/test/java/org/apache/helix/integration/controller/TestControllerLeadershipChange.java
index ee9f27720e..3066459f28 100644
--- a/helix-core/src/test/java/org/apache/helix/integration/controller/TestControllerLeadershipChange.java
+++ b/helix-core/src/test/java/org/apache/helix/integration/controller/TestControllerLeadershipChange.java
@@ -283,8 +283,6 @@ public void testMissingTopStateDurationMonitoring() throws Exception {
     // Trigger missing top state in manager1
     participant.syncStop();
 
-    Thread.sleep(1000);
-
     // Starting manager2
     HelixManager manager2 = HelixManagerFactory
         .getZKHelixManager(clusterName, clusterName + "-manager2", InstanceType.CONTROLLER,
@@ -300,8 +298,6 @@ public void testMissingTopStateDurationMonitoring() throws Exception {
     // Wait for rebalance
     Assert.assertTrue(clusterVerifier.verify());
 
-    Thread.sleep(1000);
-
     // The moment before manager1 regain leadership. The topstateless duration will start counting.
     long start = System.currentTimeMillis();
     setLeader(manager1);
diff --git a/helix-core/src/test/java/org/apache/helix/integration/controller/TestTargetExternalView.java b/helix-core/src/test/java/org/apache/helix/integration/controller/TestTargetExternalView.java
index 26bb76631b..89399954a4 100644
--- a/helix-core/src/test/java/org/apache/helix/integration/controller/TestTargetExternalView.java
+++ b/helix-core/src/test/java/org/apache/helix/integration/controller/TestTargetExternalView.java
@@ -87,7 +87,7 @@ public void testTargetExternalViewEnable() throws InterruptedException {
         _participants[0].getInstanceName(), false);
 
     Assert.assertTrue(verifier.verifyByPolling());
-    Thread.sleep(1000);
+
     targetExternalViews = _accessor.getChildValues(_accessor.keyBuilder().externalViews(), true);
     idealStates = _accessor.getChildValues(_accessor.keyBuilder().idealStates(), true);
 
diff --git a/helix-core/src/test/java/org/apache/helix/integration/manager/TestDistributedControllerManager.java b/helix-core/src/test/java/org/apache/helix/integration/manager/TestDistributedControllerManager.java
index 61922324a5..1a262fbc57 100644
--- a/helix-core/src/test/java/org/apache/helix/integration/manager/TestDistributedControllerManager.java
+++ b/helix-core/src/test/java/org/apache/helix/integration/manager/TestDistributedControllerManager.java
@@ -79,8 +79,6 @@ public void simpleIntegrationTest() throws Exception {
     // disconnect first distributed-controller, and verify second takes leadership
     distributedControllers[0].disconnect();
 
-    Thread.sleep(100);
-
     // verify leader changes to localhost_12919
     result = verifier.verifyByZkCallback();
     Assert.assertTrue(result);