Hello, if in doubt, one can always call c4d.StopAllThreads() before editing the active document from some user interaction in the main thread. This call will terminate other threads that may also currently use the active document (e.g. viewport rendering). best wishes, Sebastian

Hello, as now said multiple times, GetActiveDocument() must not be used, but GetDocument() instead. What is the point of your In/Exclude list? Are these the objects you "rotate along the timeline"? This is typically not how a ObjectData object works; it generates objects based on its child objects or deforms objects in its hierarchy. It is not supposed to move arbitrary other objects. As mentioned above, a tag plugin may be the better solution. The "look_at_camera" example show such a plugin rotating its host object. best wishes, Sebastian

Fantastic, Thank you for the suggestions, ObjectDataOptimizeCache(true) does what I need.