I have a tree with a terrible performance, profiling I saw that the function I have attached to the selectionchange event of the selection model is called tons of times when you collapse a node. I created a small test case for this, you can run it and check the console when the root is collapsed:

    <title>ExtJS Example</title>
    <link rel="stylesheet" type="text/css" href="javascript/extjs/resources/css/ext-all.css"/>
    <script type="text/javascript" src="javascript/extjs/ext-all-debug.js"></script>

    <script type="text/javascript">
            var root = {text : 'root', children :[]},
                counter = 0;
            for (var i = 0; i < 99; i++)
                root.children.push({text : 'child'+i, leaf:true});
                layout: 'border',
                        title : 'tree',
                        region: 'west',
                        split: true,
                        width: 300,
                        selModel : Ext.create('Ext.selection.RowModel', 
                            listeners : 
                                selectionChange : function()
                        store : Ext.create('Ext.data.TreeStore',
                            root : root
This is a performance killer if you have a function slightly more complex than the one I added in this code...

I am the only one that found this? If this is not a bug, please explain the behavior and move the topic to the correct forum.