When you apply an animation to a property using the Compose HandoffBehavior, any clocks objects previously associated with that property continue to consume system resources; the timing system will not remove these clocks automatically.
To avoid performance issues when you apply a large number of clocks using HandofffBehavior.Compose, you should remove composing clocks from the animated property after they complete. There are several ways to remove a clock.
This is primarily an issue for animations on objects that have a long lifetime. When an object is garbage collected, its clocks will also be disconnected and garbage collected.