diff --git a/zkdoc/release-note b/zkdoc/release-note
index eadfa4f7d8b..261135af201 100644
--- a/zkdoc/release-note
+++ b/zkdoc/release-note
@@ -7,6 +7,7 @@ ZK 10.0.0
   ZK-5579: Listbox always renders the same set of items under ROD enabled
   ZK-5582: Listbox only renders 50 items with client mvvm
   ZK-5476: client mvvm failed for a tree
+  ZK-5535: TrackerImplEx#removeAllReference accesses map value by iteration instead of key, lowers performance
 
 * Upgrade Notes
 
diff --git a/zktest/build.gradle b/zktest/build.gradle
index 797241d135d..43b4ee937f2 100644
--- a/zktest/build.gradle
+++ b/zktest/build.gradle
@@ -238,6 +238,9 @@ test {
 	testLogging {
 		events("standardOut", "started", "passed", "skipped", "failed")
 	}
+
+	maxHeapSize = "1024m"
+	jvmArgs '-XX:MaxPermSize=1024m'
 }
 
 task clearNoA11Y(type: Delete) {
diff --git a/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/Bug.java b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/Bug.java
new file mode 100644
index 00000000000..e1f7e663300
--- /dev/null
+++ b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/Bug.java
@@ -0,0 +1,112 @@
+package org.zkoss.zktest.test2.B100_ZK_5535;
+
+import org.zkoss.bind.BindUtils;
+import org.zkoss.bind.annotation.Command;
+public class Bug {
+	private BugOasiListBoxLayoutModel gridTree=new BugOasiListBoxLayoutModel();
+	public BugOasiListBoxLayoutModel getGridTree() {
+		return gridTree;
+	}
+	public void setGridTree(BugOasiListBoxLayoutModel gridTree) {
+		this.gridTree = gridTree;
+	}
+	public Bug()
+    {
+    }
+	public void loadDati()
+	{
+		BugOasiTreeNode<BugFormModel> nodeParent=this.loadDati(null);
+		for (int i=0;i<2000;i++)
+		    nodeParent=this.loadDati(nodeParent);
+		this.gridTree.setLeafNodes();
+	}
+	public BugOasiTreeNode<BugFormModel> loadDati(
+			BugOasiTreeNode<BugFormModel> parent)
+	{
+		BugFormModel row=null;
+		/* --------------------------------------- */
+		/* Popolo grid tree                        */
+		/* --------------------------------------- */
+		BugOasiTreeNode<BugFormModel> nodeParent;
+		BugOasiTreeNode<BugFormModel> node;
+		/* ------------------------- */
+		/* Creo nodo di root         */
+		/* ------------------------- */
+		nodeParent=gridTree.addTreeNode(parent,true);
+		row=nodeParent.getData();
+		row.get("coarfo").setStringVal("1");
+		row.get("descri").setStringVal("Nodo root");
+		nodeParent=gridTree.addTreeNode(true);
+		row=nodeParent.getData();
+		row.get("coarfo").setStringVal("1");
+		row.get("descri").setStringVal("Nodo root2");
+		nodeParent=gridTree.addTreeNode(true);
+		row=nodeParent.getData();
+		row.get("coarfo").setStringVal("1");
+		row.get("descri").setStringVal("Nodo root3");
+		nodeParent=gridTree.addTreeNode(true);
+		row=nodeParent.getData();
+		row.get("coarfo").setStringVal("1");
+		row.get("descri").setStringVal("Nodo root4");
+		nodeParent=gridTree.addTreeNode(true);
+		row=nodeParent.getData();
+		row.get("coarfo").setStringVal("1");
+		row.get("descri").setStringVal("Nodo root5");
+		nodeParent=gridTree.addTreeNode(true);
+		row=nodeParent.getData();
+		row.get("coarfo").setStringVal("1");
+		row.get("descri").setStringVal("Nodo root6");
+		/* ---------------------------------- */
+		/* Creo primo nodo figlio senza figli */
+		/* ---------------------------------- */
+		node=gridTree.addTreeNode(nodeParent);
+		node.setLeaf(true);
+		row=node.getData();
+		row.get("coarfo").setStringVal("2");
+		row.get("descri").setStringVal("nodo figlio 1");
+		/* ---------------------------------- */
+		/* Creo secondo nodo figlio con figli */
+		/* ---------------------------------- */
+		node=gridTree.addTreeNode(nodeParent,false);
+		row=node.getData();
+		row.get("coarfo").setStringVal("3");
+		row.get("descri").setStringVal("nodo figlio 2");
+		/* ---------------------------------- */
+		/* Creo figli secondo nodo figlio     */
+		/* ---------------------------------- */
+		nodeParent=node;
+		node=gridTree.addTreeNode(nodeParent,true);
+		row=node.getData();
+		row.get("coarfo").setStringVal("4");
+		row.get("descri").setStringVal("primo figlio del cocondo figlio");
+		/* ---------------------------------- */
+		/* Creo secondo nodo figlio con figli */
+		/* ---------------------------------- */
+		node=gridTree.addTreeNode(nodeParent,true);
+		row=node.getData();
+		row.get("coarfo").setStringVal("6");
+		row.get("descri").setStringVal("secondo figlio del cocondo figlio");
+		/* ---------------------------------- */
+		/* Creo figlio in mezzo               */
+		/* ---------------------------------- */
+		node=gridTree.addTreeNode(nodeParent,true,1);
+		row=node.getData();
+		row.get("coarfo").setStringVal("5");
+		row.get("descri").setStringVal("creato figlio in mezzo");
+		
+		return nodeParent;
+	}
+	@Command
+	public void showData()
+	{
+		this.loadDati();
+		BindUtils.postNotifyChange(null, null, this, "gridTree");
+	}
+	@Command
+	public void clearTree()
+	{
+		this.gridTree.clearTree();
+		BindUtils.postNotifyChange(null, null, this, "gridTree");
+	}
+}
+
diff --git a/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugFieldLayout.java b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugFieldLayout.java
new file mode 100644
index 00000000000..c79c9227bba
--- /dev/null
+++ b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugFieldLayout.java
@@ -0,0 +1,17 @@
+package org.zkoss.zktest.test2.B100_ZK_5535;
+
+public class BugFieldLayout {
+private String stringVal;
+
+public String getStringVal() {
+	return stringVal;
+}
+
+public void setStringVal(String stringVal) {
+	this.stringVal = stringVal;
+}
+public void detach()
+{
+	this.stringVal=null;
+}
+}
diff --git a/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugFormModel.java b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugFormModel.java
new file mode 100644
index 00000000000..1cb87d3d3af
--- /dev/null
+++ b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugFormModel.java
@@ -0,0 +1,56 @@
+package org.zkoss.zktest.test2.B100_ZK_5535;
+
+import java.util.LinkedHashMap;
+import java.util.Map.Entry;
+public class BugFormModel  {
+public LinkedHashMap<String, BugFieldLayout> fields = new LinkedHashMap<String, BugFieldLayout>();
+private BugOasiTreeNode<BugFormModel> node=null;
+
+/**
+ * <LI>BugFormModel</LI>
+ * <PRE>
+ * Nel caso di un Tree restituisce il nodo associato
+ * </PRE>
+ *  
+ * @author m.spuri
+ */
+public BugOasiTreeNode<BugFormModel> getNode() {
+	return node;
+}
+/**
+ * <LI>BugFormModel</LI>
+ * <PRE>
+ * Nel caso di un Tree restituisce il nodo associato
+ * </PRE>
+ *  
+ * @author m.spuri
+ */
+public void setNode(BugOasiTreeNode<BugFormModel> node) {
+	this.node = node;
+}
+public LinkedHashMap<String, BugFieldLayout> getFields() {
+	return fields;
+}
+public void setFields(LinkedHashMap<String, BugFieldLayout> fields) {
+	this.fields = fields;
+}
+public BugFieldLayout get(String name)
+{
+	return fields.get(name);
+}
+public BugFormModel()
+{
+	fields.put("coarfo",new BugFieldLayout());
+	fields.put("descri",new BugFieldLayout());
+}
+public void detach()
+{	
+	if ( this.fields!=null )
+	{
+		for(Entry<String, BugFieldLayout> obj: this.fields.entrySet())
+			obj.getValue().detach();
+		this.fields.clear();
+		this.fields=null;
+	}
+}
+}
diff --git a/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugOasiListBoxLayoutModel.java b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugOasiListBoxLayoutModel.java
new file mode 100644
index 00000000000..1ae9bfa0c93
--- /dev/null
+++ b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugOasiListBoxLayoutModel.java
@@ -0,0 +1,178 @@
+package org.zkoss.zktest.test2.B100_ZK_5535;
+
+import java.util.LinkedList;
+
+import org.zkoss.zul.DefaultTreeModel;
+import org.zkoss.zul.TreeModel;
+import org.zkoss.zul.TreeNode;
+public class BugOasiListBoxLayoutModel {
+	private BugOasiTreeNode<BugFormModel> treeRoot = null;
+	private TreeModel<TreeNode<BugFormModel>> treeNodes = null;
+	private boolean enableMultiSelection = false;
+	public boolean isEnableMultiSelection() {
+		return enableMultiSelection;
+	}
+
+	public void setEnableMultiSelection(boolean enableMultiSelection) {
+		this.enableMultiSelection = enableMultiSelection;
+	}
+
+	public BugOasiTreeNode<BugFormModel> getTreeRoot() {
+		return treeRoot;
+	}
+
+	public void setTreeRoot(BugOasiTreeNode<BugFormModel> treeRoot) {
+		this.treeRoot = treeRoot;
+	}
+	public TreeModel<TreeNode<BugFormModel>> getTreeNodes() {
+		return this.treeNodes;
+	}
+
+	public void setTreeNodes(TreeModel<TreeNode<BugFormModel>> treeNodes) {
+		this.treeNodes = treeNodes;
+	}
+	/**
+	 * <LI>OasiListBoxLayoutModel</LI>
+	 * 
+	 * <PRE>
+	 * Aggiunge un nodo al tree
+	 * </PRE>
+	 * 
+	 * Aggiungo nodo di root
+	 * 
+	 * @author m.spuri
+	 */
+	public BugOasiTreeNode<BugFormModel> addTreeNode(boolean open) {
+		return this.addTreeNode(null, open);
+	}/**
+	 * <LI>OasiListBoxLayoutModel</LI>
+	 * 
+	 * <PRE>
+	 * Aggiunge un nodo al tree
+	 * </PRE>
+	 * 
+	 * @author m.spuri
+	 */
+	public BugOasiTreeNode<BugFormModel> addTreeNode(
+			BugOasiTreeNode<BugFormModel> parent,
+			boolean open) {
+		return this.addTreeNode(parent, open, null);
+	}
+	public BugOasiTreeNode<BugFormModel> addTreeNode(
+			BugOasiTreeNode<BugFormModel> parent,
+			boolean open, Integer pos) {
+		return this.addTreeNode(parent, null, null, open, pos);
+	}
+	private BugOasiTreeNode<BugFormModel> addTreeNode(
+			BugOasiTreeNode<BugFormModel> parent,
+			BugOasiTreeNode<BugFormModel> newnod, BugFormModel myrow, boolean open,
+			Integer pos) {
+		if (parent == null) {
+			if (this.treeRoot == null)
+				this.createTreeRoot();
+			parent = this.treeRoot;
+		}
+		BugFormModel row;
+		if (newnod == null) {
+			if (myrow == null)
+				row = new BugFormModel();
+			else
+				row = myrow;
+		} else
+			row = newnod.getData();
+		
+		
+		BugOasiTreeNode<BugFormModel> treeNode = null;
+		if (newnod == null)
+			treeNode = new BugOasiTreeNode<BugFormModel>(parent, row,
+					new LinkedList<BugOasiTreeNode<BugFormModel>>(), treeNodes, open,
+					pos);
+		else {
+			treeNode = newnod;
+			parent.setLeaf(false);
+			if (pos == null)
+				parent.add(treeNode);
+			else
+				parent.getChildren().add(pos, treeNode);
+		}
+		row.setNode(treeNode);
+		if (treeNode.isOpen())
+			((DefaultTreeModel<BugFormModel>) treeNodes).addOpenObject(treeNode);
+		return treeNode;
+	}
+	private void createTreeRoot() {
+		this.treeRoot = new BugOasiTreeNode<BugFormModel>(null,
+				new LinkedList<BugOasiTreeNode<BugFormModel>>(), treeNodes, true);
+		
+		this.treeNodes = new DefaultTreeModel<BugFormModel>(this.treeRoot);
+		((DefaultTreeModel<BugFormModel>)this.treeNodes).setMultiple(this.isEnableMultiSelection());
+	}
+	/**
+	 * <LI>OasiListBoxLayoutModel</LI>
+	 * 
+	 * <PRE>
+	 * Aggiunge un nodo al tree
+	 * </PRE>
+	 * 
+	 * Di default � chiuso
+	 * 
+	 * @author m.spuri
+	 */
+	public BugOasiTreeNode<BugFormModel> addTreeNode(
+			BugOasiTreeNode<BugFormModel> parent) {
+		return this.addTreeNode(parent, false);
+	}
+	
+	public void clearTree() {
+		int n;
+		if (this.treeRoot != null) {
+			n = this.treeRoot.getChildren().size();
+			for (int k = 0; k < n; k++)
+				this.clearTreeNode((BugOasiTreeNode<BugFormModel>) this.treeRoot.getChildren().get(k));
+			try {
+				this.treeRoot.getChildren().clear();
+			} catch (Exception e) {
+				// TODO: handle exception
+			}
+
+			this.treeRoot = null;
+		}
+	}
+	private  void clearTreeNode(BugOasiTreeNode<BugFormModel> node) {
+		if (node == null)
+			return;
+		if (!node.isLeaf() && node.isOpen())
+			((DefaultTreeModel<BugFormModel>) treeNodes).removeOpenObject(node);
+		
+		BugFormModel row = (BugFormModel) node.getData();
+		row.detach();
+		if (node.getChildren() != null) {
+			int n = node.getChildren().size();
+			for (int i = 0; i < n; i++) {
+				this.clearTreeNode((BugOasiTreeNode<BugFormModel>) node.getChildren().get(i));
+			}
+			node.getChildren().clear();
+		}
+	}
+	public void setLeafNodes() {
+		int n;
+		if (this.treeRoot != null) {
+			n = this.treeRoot.getChildren().size();
+			for (int k = 0; k < n; k++)
+				this.setLeaf((BugOasiTreeNode<BugFormModel>) this.treeRoot.getChildren().get(k));
+		}
+	}
+	private  void setLeaf(BugOasiTreeNode<BugFormModel> node) {
+		if (node == null)
+			return;
+		if (node.getChildren() != null && node.getChildren().size()>0 ) {
+			int n = node.getChildren().size();
+			for (int i = 0; i < n; i++) {
+				this.setLeaf((BugOasiTreeNode<BugFormModel>) node.getChildren().get(i));
+			}
+		}
+		else
+			node.setLeaf(true);
+	}
+
+}
diff --git a/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugOasiTreeNode.java b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugOasiTreeNode.java
new file mode 100644
index 00000000000..0ce4fef7369
--- /dev/null
+++ b/zktest/src/main/java/org/zkoss/zktest/test2/B100_ZK_5535/BugOasiTreeNode.java
@@ -0,0 +1,96 @@
+package org.zkoss.zktest.test2.B100_ZK_5535;
+
+import java.util.LinkedList;
+import org.zkoss.zul.DefaultTreeModel;
+import org.zkoss.zul.DefaultTreeNode;
+import org.zkoss.zul.TreeModel;
+import org.zkoss.zul.TreeNode;
+
+public class BugOasiTreeNode<T> extends DefaultTreeNode<T> {
+	private static final long serialVersionUID = -8085873079938209759L;
+	
+	// Node Control the default open
+	private boolean open = false;
+	private boolean leafNode=true;
+	private TreeModel<TreeNode<T>> treeNodes=null;
+	public BugOasiTreeNode(T data, LinkedList<BugOasiTreeNode<T>> children, TreeModel<TreeNode<T>>treeNodes,boolean open) {
+		super(data, children);
+		this.treeNodes=treeNodes;
+		if ( this.treeNodes!=null )
+			this.setOpen(open);
+		else
+		    this.open=open;
+	}
+	public BugOasiTreeNode(BugOasiTreeNode<T> parent,T data, LinkedList<BugOasiTreeNode<T>> children, TreeModel<TreeNode<T>>treeNodes,boolean open) {
+		super(data, children);
+		this.treeNodes=treeNodes;
+		this.setOpen(open);
+		parent.setLeaf(false);
+		parent.add(this);
+	}
+	public BugOasiTreeNode(BugOasiTreeNode<T> parent,T data, LinkedList<BugOasiTreeNode<T>> children,TreeModel<TreeNode<T>>treeNodes, boolean open,Integer pos) {
+		super(data, children);
+		this.treeNodes=treeNodes;
+		this.setOpen(open);
+		parent.setLeaf(false);
+		if (pos==null || parent.getChildren().size()==0 )
+		    parent.add(this);
+		else
+			parent.getChildren().add(pos,this);
+	}
+	public BugOasiTreeNode(T data, LinkedList<BugOasiTreeNode<T>> children,TreeModel<TreeNode<T>>treeNodes) {
+		super(data, children);
+		this.treeNodes=treeNodes;
+	}
+	public BugOasiTreeNode(BugOasiTreeNode<T> parent,T data, LinkedList<BugOasiTreeNode<T>> children,TreeModel<TreeNode<T>>treeNodes) {
+		super(data, children);
+		parent.setLeaf(false);
+		parent.add(this);
+		this.treeNodes=treeNodes;
+	}
+
+	public BugOasiTreeNode(BugOasiTreeNode<T> parent,T data,TreeModel<TreeNode<T>>treeNodes) {
+		super(data);
+		parent.setLeaf(false);
+		parent.add(this);
+		this.treeNodes=treeNodes;
+	}
+	public BugOasiTreeNode(BugOasiTreeNode<T> parent,T data,boolean open,TreeModel<TreeNode<T>>treeNodes) {
+		super(data);
+		parent.setLeaf(false);
+		parent.add(this);
+		this.treeNodes=treeNodes;
+		this.setOpen(open);
+	}
+	public BugOasiTreeNode(T data,TreeModel<TreeNode<T>>treeNodes) {
+		super(data);
+		this.treeNodes=treeNodes;
+	}
+	public BugOasiTreeNode(T data,TreeModel<TreeNode<T>>treeNodes,boolean open) {
+		super(data);
+		this.treeNodes=treeNodes;
+		this.setOpen(open);
+	}
+
+	public boolean isOpen() {
+		return open;
+	}
+
+	public void setOpen(boolean open) {
+		this.open = open;
+		if ( open )
+	        ((DefaultTreeModel<T>)treeNodes).addOpenObject(this);
+		else
+			((DefaultTreeModel<T>)treeNodes).removeOpenObject(this);
+	}
+	public boolean isLeaf() {
+		
+			 return leafNode;
+	}
+	public void setLeaf(boolean value) {
+		
+		 this.leafNode=value;
+		 if ( value )
+			 this.setOpen(false);
+    }
+}
diff --git a/zktest/src/main/webapp/test2/B100-ZK-5535.zul b/zktest/src/main/webapp/test2/B100-ZK-5535.zul
new file mode 100644
index 00000000000..9f4025486b4
--- /dev/null
+++ b/zktest/src/main/webapp/test2/B100-ZK-5535.zul
@@ -0,0 +1,76 @@
+<?page title="new page title" contentType="text/html;charset=UTF-8"?>
+<zk>
+	<label multiline="true">
+		1. Click "Show Data" button.
+		2. Click "Clear Tree" (if it takes over 40 sec., it's a bug).
+	</label>
+<window width="100%" border="none" apply="org.zkoss.bind.BindComposer"  viewModel="@id('vm') @init('org.zkoss.zktest.test2.B100_ZK_5535.Bug')" >
+<button label="Show Data" id="show" onClick="@command('showData')"/><button id="clear" label="Clear Tree" onClick="@command('clearTree')"/>
+<tree sizedByContent="true"  model="@bind(vm.gridTree.treeNodes)"  mold="paging" pageSize="20"  >
+<treecols  sizable="true" >
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+<treecol label="Code" />
+<treecol label="Description" />
+</treecols>
+<template name="model">
+<treeitem>
+<treerow>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+<treecell label="@bind(each.data.fields['coarfo'].stringVal)"/>
+<treecell label="@bind(each.data.fields['descri'].stringVal)"/>
+</treerow>
+</treeitem>
+</template>
+</tree>
+</window>
+</zk>
\ No newline at end of file
diff --git a/zktest/src/main/webapp/test2/config.properties b/zktest/src/main/webapp/test2/config.properties
index 9f50fabafa1..904ff472e22 100644
--- a/zktest/src/main/webapp/test2/config.properties
+++ b/zktest/src/main/webapp/test2/config.properties
@@ -3131,6 +3131,7 @@ B90-ZK-4431.zul=A,E,Multislider
 ##manually##B96-ZK-5061.zul=A,E,embedded,CSS
 ##zats##B96-ZK-5379.zul=A,E,scroll,floatingScrollbar,anchornav
 ##zats##B96-ZK-5414.zul=A,E,timer,cascader
+##zats##B96-ZK-5535.zul=A,E,performance,tree,mvvm,trackerNode,treeModel
 
 ## B100
 ##zats##B100-ZK-5089.zul=A,E,Window,AfterSizeEvent
diff --git a/zktest/src/test/java/org/zkoss/zktest/zats/test2/B100_ZK_5535Test.java b/zktest/src/test/java/org/zkoss/zktest/zats/test2/B100_ZK_5535Test.java
new file mode 100644
index 00000000000..f77960e372a
--- /dev/null
+++ b/zktest/src/test/java/org/zkoss/zktest/zats/test2/B100_ZK_5535Test.java
@@ -0,0 +1,35 @@
+/* B100_ZK_5535Test.java
+
+	Purpose:
+		
+	Description:
+		
+	History:
+		12:4PM 2023/12/1, Created by jumperchen
+
+Copyright (C) 2023 Potix Corporation. All Rights Reserved.
+*/
+package org.zkoss.zktest.zats.test2;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+
+import org.junit.jupiter.api.Test;
+
+import org.zkoss.test.webdriver.WebDriverTestCase;
+
+/**
+ * @author jumperchen
+ */
+public class B100_ZK_5535Test extends WebDriverTestCase {
+
+	@Test
+	public void testPerformance() {
+		connect();
+		click(jq("$show"));
+		sleep(35_000);
+		waitResponse();
+		click(jq("$clear"));
+		sleep(5_000);
+		assertFalse(jq(".z-loading-indicator").exists());
+	}
+}
diff --git a/zul/src/main/java/org/zkoss/zul/AbstractTreeModel.java b/zul/src/main/java/org/zkoss/zul/AbstractTreeModel.java
index d8cda4e9dca..b0db4865275 100644
--- a/zul/src/main/java/org/zkoss/zul/AbstractTreeModel.java
+++ b/zul/src/main/java/org/zkoss/zul/AbstractTreeModel.java
@@ -192,7 +192,7 @@ public void fireEvent(int evtType, int[] path, int indexFrom, int indexTo) {
 	/**
 	 * Has the same functionality with {@link #fireEvent(int, int[], int, int)},
 	 * while this is used for node removal only
-	 * 
+	 *
 	 * @since 7.0.5
 	 */
 	public void fireEvent(int evtType, int[] path, int indexFrom, int indexTo, int[] affectedPath) {
@@ -201,6 +201,18 @@ public void fireEvent(int evtType, int[] path, int indexFrom, int indexTo, int[]
 			l.onChange(evt);
 	}
 
+	/**
+	 * Has the same functionality with {@link #fireEvent(int, int[], int, int)},
+	 * while this is used for node removal only
+	 *
+	 * @since 10.0.0
+	 */
+	public void fireEvent(int evtType, int[] path, int indexFrom, int indexTo, int[][] affectedPaths) {
+		final TreeDataEvent evt = new TreeDataEvent(this, evtType, path, indexFrom, indexTo, affectedPaths);
+		for (TreeDataListener l : _listeners)
+			l.onChange(evt);
+	}
+
 	/**
 	 * Fires a {@link TreeDataEvent} for all registered listener when selection
 	 * status has changed.
diff --git a/zul/src/main/java/org/zkoss/zul/DefaultTreeNode.java b/zul/src/main/java/org/zkoss/zul/DefaultTreeNode.java
index 580e223bfdb..62dd9cf3902 100644
--- a/zul/src/main/java/org/zkoss/zul/DefaultTreeNode.java
+++ b/zul/src/main/java/org/zkoss/zul/DefaultTreeNode.java
@@ -254,6 +254,36 @@ public void add(int index, TreeNode<E> child) {
 
 		}
 
+		protected void removeRange(int fromIndex, int toIndex) {
+			if (fromIndex == toIndex - 1) {
+				// single one
+				super.removeRange(fromIndex, toIndex);
+			} else {
+				// a batch mode
+				DefaultTreeModel<E> model = getModel();
+				List<int[]> paths = new ArrayList<>(toIndex - fromIndex + 1);
+				for (int i = 0, n = toIndex - fromIndex; i < n; i++) {
+
+					TreeNode<E> child = _list.get(fromIndex);
+
+					if (model != null) {
+						paths.add(model.getPath(child));
+					}
+					_list.remove(fromIndex);
+					if (child instanceof DefaultTreeNode)
+						((DefaultTreeNode<E>) child).setParent(null);
+				}
+
+				if (model != null) {
+					int[][] pathsArray = paths.toArray(new int[0][]);
+					model.removeSelectionPaths(pathsArray);
+					model.removeOpenPaths(pathsArray);
+					model.fireEvent(TreeDataEvent.INTERVAL_REMOVED, model.getPath(DefaultTreeNode.this), fromIndex,
+							toIndex, pathsArray);
+				}
+			}
+		}
+
 		public TreeNode<E> remove(int index) {
 
 			DefaultTreeModel<E> model = getModel();
diff --git a/zul/src/main/java/org/zkoss/zul/event/TreeDataEvent.java b/zul/src/main/java/org/zkoss/zul/event/TreeDataEvent.java
index 9d0f1e2302b..4e5fbe5ed78 100644
--- a/zul/src/main/java/org/zkoss/zul/event/TreeDataEvent.java
+++ b/zul/src/main/java/org/zkoss/zul/event/TreeDataEvent.java
@@ -58,6 +58,7 @@ public class TreeDataEvent {
 	private final int _indexTo;
 	private final int[] _nodePath;
 	private final int[] _affectedPath;
+	private final int[][] _affectedPaths;
 
 	/** Constructor.
 	 *
@@ -79,6 +80,7 @@ public TreeDataEvent(TreeModel model, int type, int[] nodePath, int indexFrom, i
 		_indexFrom = indexFrom;
 		_indexTo = indexTo;
 		_affectedPath = null;
+		_affectedPaths = null;
 	}
 
 	/** Constructor.
@@ -102,6 +104,36 @@ public TreeDataEvent(TreeModel model, int type, int[] nodePath, int indexFrom, i
 		_indexFrom = indexFrom;
 		_indexTo = indexTo;
 		_affectedPath = affectedPath;
+		_affectedPaths = new int[][] {affectedPath};
+	}
+
+	/** Constructor.
+	 *
+	 * @param type one of {@link #CONTENTS_CHANGED},
+	 * {@link #INTERVAL_ADDED}, {@link #INTERVAL_REMOVED}, {@link #SELECTION_CHANGED},
+	 * {@link #OPEN_CHANGED}, {@link #STRUCTURE_CHANGED} or {@link #MULTIPLE_CHANGED}.
+	 * @param nodePath the path of the affected node.
+	 * If {@link #CONTENTS_CHANGED}, {@link #INTERVAL_ADDED} or {@link #INTERVAL_REMOVED},
+	 * it is the parent node. If {@link #SELECTION_CHANGED} or {@link #OPEN_CHANGED},
+	 * it is the node being selected or opened.
+	 * If {@link #STRUCTURE_CHANGED} or {@link #MULTIPLE_CHANGED}, it is null.
+	 * @param indexFrom the lower index of the change range
+	 * @param indexTo the upper index of the change range
+	 * @param affectedPaths the paths to be removed or added
+	 * @since 10.0.0
+	 */
+	public TreeDataEvent(TreeModel model, int type, int[] nodePath, int indexFrom, int indexTo, int[][] affectedPaths) {
+		_model = model;
+		_type = type;
+		_nodePath = nodePath;
+		_indexFrom = indexFrom;
+		_indexTo = indexTo;
+		if (affectedPaths != null && affectedPaths.length > 0) {
+			_affectedPath = affectedPaths[0];
+		} else {
+			_affectedPath = null;
+		}
+		_affectedPaths = affectedPaths;
 	}
 
 	/** Returns the tree model that fires this event.
@@ -153,4 +185,12 @@ public int[] getAffectedPath() {
 		return _affectedPath;
 	}
 
+	/**
+	 * Return the paths of removed nodes, if any.
+	 * @since 10.0.0
+	 */
+	public int[][] getAffectedPaths() {
+		return _affectedPaths;
+	}
+
 }