RadTimeline throws OutOfMemoryException when you zoom to a small interval type (e.g. SecondInterval, MillisecondInterval) in case the control visualizes a very large period (e.g. 2-3 years). As a workaround you can limit the depth to which you can zoom using a larger value for the MinZoomRange property. Another way to go is to increase the IntervalSpans of the Interval. For example set IntervalSpans=500 in MillisecondInterval.