: I think it's just supposed to be part of her alien personality. Maybe there is a physiological reason for it, but I missed the episode that introduced Chiana.

Ya, it's probably the Nembari alein personalty. There wasn't any comment about it in the episode she was introduced, but her jailer, Salis, had the same kind of slow/snappy methodical movements, but they were much less exagerated (or more repressed, him being the conservitive tight type that he was).