I have observed your requirements and like to share that slide cloning (copying slides from other presentations) operation does not consume much time. However, presentation loading and copying depends on many factors in which presentation size and number of slides are considerable factors. Moreover, it also depends upon the number of shapes and type of content inside slide (like multimedia content and images). Therefore, there is no specific benchmark available as it will vary from presentation to presentation based on factors mentioned before. I suggest you to please try using Aspose.Slides in your environment and perform the desired operations.