I've been using Preview a lot today because I'm reading/studying PDF documents for a midterm. It was working fine an hour ago, but now that I'm looking at a different PDF document, it's really slow. The text in the document is small, so I have to zoom in, but it takes like 2-3 seconds for it to zoom in. When I scroll from top-to-bottom or side-to-side, it takes like 5 seconds for it to take effect. Anyone else have this problem and how do I fix it?