This is just an FYI when you go to Preview a slide(s) and the system is slow or crashes. I have found when the Animation Pane is open and you want to Preview a slide(s), the system slows to a crawl and sometimes crashes. When I close the Animation Pane everything is fine and previews fast. Since I use the Animation Pane often, it's a pain when I forget to close it and try to preview a slide.
Just an FYI for someone having issues regarding the system slowing down when previewing their work.