# Tree View Virtualization ## Content [C1TreeView](/componentone/api/wpf/online-basiclibrary/dotnet-framework-api/C1.WPF.4.6.2/C1.WPF.C1TreeView.html) supports UI virtualization for hierarchical data. Virtualization is an optimization to avoid constructing and rendering the container objects for items that are not visible. When the virtualization is enabled for **C1TreeView** it creates only the treeview items needed to display the items that are visible on screen. For example, suppose we have a **C1TreeView** with 10,000 items, but only 50 are visible at any time.Without virtualization, the **C1TreeView** would take a long time to render 10,000 treeview items even though only 50 treeview items are visbile.With virtualization the **C1TreeView** would only create what is needed to display in this case only 50 treeview items. As a result, using virtualization when needed would improve performance. The UI Virtualization is disabled in **C1TreeView**, by default. To enable it you can use the following markup: ```xml ```