# Virtualization

The MultiColumnComboBox supports UI virtualization which provides options for significantly improving the performance when working with large datasets.

Regardless of the dataset size, the virtualization technique uses a fixed amount of DOM elements in the popup list of the component. When the list is scrolled, the component displays the relevant data by reusing the existing elements instead of creating new ones.

## Enabling Virtualization

To enable the virtual scrolling, pass a [`VirtualizationSettings`](https://www.telerik.com/kendo-angular-ui/components/dropdowns/api/virtualizationsettings) object to the [`virtual`](https://www.telerik.com/kendo-angular-ui/components/dropdowns/api/multicolumncomboboxcomponent#virtual) input property and specify the desired [`itemHeight`](https://www.telerik.com/kendo-angular-ui/components/dropdowns/api/virtualizationsettings#itemheight).

Although rarely needed, you can control the number of DOM elements that the list will render through the [`pageSize`](https://www.telerik.com/kendo-angular-ui/components/dropdowns/api/virtualizationsettings#pagesize) property. By default, the MultiColumnComboBox uses a virtual page size of 30 rows.

[Demo Source](https://demos.telerik.com/kendo-angular-ui/demos/dropdowns/multicolumncombobox/virtualization/basic-setup/source.txt)

## Using with Grouping and Filtering

The following example demonstrates how to use the virtualization functionality of the MultiColumnComboBox with grouping and filtering.

[Demo Source](https://demos.telerik.com/kendo-angular-ui/demos/dropdowns/multicolumncombobox/virtualization/grouping-integration/source.txt)

## Suggested Links

* [API Reference of the ComboBox](https://www.telerik.com/kendo-angular-ui/components/dropdowns/api/multicolumncomboboxcomponent)