Set OwnerData to true to specify that the list view is virtual. A virtual list view can contain a huge number of items (specifically, up to a DWORD). However, you must manage the items of a virtual list view using the OnData, OnDataFind, OnDataHint, and OnDataStateChange event handlers. For example, you must explicitly provide a value to a list item's StateIndex property if it is to display a check box. 

When creating a virtual list view, you must set the Count property for the Items to the number of items in the virtual list. 

The only information contained in a virtual list view control is the selection and focus information. 

To improve the performance of a virtual list view control, cache items for quick retrieval. The OnDataHint event can help optimize retrieval from the cache.

OnData 

OnDataFind 

OnDataHint 

OnDataStateChange 

OwnerDraw 

Count