when we are typing text in the dropdown value display input box, we do not do a postback (filtering) on every key stroke but instead use a timeout and do a postback after this timeout duration. This property allows the developer to configure this timeout
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2