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.
Although rarely needed, you can control the number of DOM elements that the list will render through the
pageSize property. By default, the MultiColumnComboBox uses a virtual page size of 30 rows.