ASP.NET TreeView + AJAX

我有一个树视图，用来显示目录结构。我试图通过在节点扩展上加载子节点来减少加载时间。有办法做到这一点吗？

以下是我目前用于填充树视图的代码：

protected void Page_Load(object sender, EventArgs e) {
    BuildTree(Request.QueryString["path"]);
}
private void BuildTree(string dirPath)
{
    //get root directory
    System.IO.DirectoryInfo rootDir = new System.IO.DirectoryInfo(dirPath);
    //create and add the root node to the tree view
    TreeNode rootNode = new TreeNode(rootDir.Name, rootDir.FullName);
    TreeView1.Nodes.Add(rootNode);
    //begin recursively traversing the directory structure
    TraverseTree(rootDir, rootNode);
}
private void TraverseTree(System.IO.DirectoryInfo currentDir, TreeNode currentNode)
{
    //loop through each sub-directory in the current one
    foreach (System.IO.DirectoryInfo dir in currentDir.GetDirectories())
    {
            //create node and add to the tree view
            TreeNode node = new TreeNode(dir.Name, dir.FullName);
            currentNode.ChildNodes.Add(node);
            //recursively call same method to go down the next level of the tree
            TraverseTree(dir, node);
    }
    foreach (System.IO.FileInfo file in currentDir.GetFiles())
    {
        TreeNode node = new TreeNode(file.Name, file.FullName);
        currentNode.ChildNodes.Add(node);
    }
}