RadCarousel is a dynamic control, which utilizes a lot of animations in order to bring rich interactivity. Because of this, there are a few performance considerations that you have to keep in mind when working with the control:
Size of the images that you are using in the carousel items. Avoid large images, because they have a performance penalty on the animations. Here is a blog post where the author seems to have implemented a method that shows exactly how to manipulate large images: Create a Scaled Thumbnail with GDI+
Item Reflections are calculated dynamically, and impact performance. If you are using reflections, try setting the ItemReflectionPercentage property to a lower value (even zero) to see whether this helps.
Transparent background consider turning off transparency (if your carousel is set with a transparent background) by setting a Carousel background image that mixes well with the form background.A very good example that demonstrates the RadCarousel with a well-mixed background is located in the Quick Start Framework under RadCarousel-> Music Library.
Number of items that you have in the carousel. Generally speaking, having more than 10 items will slow it down, especially if some of the above items are true.