RadControls for ASP.NET AJAX AnimationDuration defines the length of the slide animation
in milliseconds. Setting AnimationDuration to a value larger than 0, will
cause the drag slider and selected region to be updated using a linear
animation By default AnimationDuration value is 100 (ms). To disable
slide animation set AnimationDuration to 0.
CopyASPX
<telerik:radslider id="RadSlider1" runat="server" animationduration="500" />
CopyC#
RadSlider1.AnimationDuration = 500;
CopyVB.NET
RadSlider1.AnimationDuration = 500