My 2018 Macbook pro currently running Mojave v 10.14.5. After the last update, I have experienced immense computer freezing and/or lag when working on PDFs (and only when working on PDFs). Actions that cause the problem include: downloading PDF (regardless of size), moving PDF from one folder to another, saving a PDF after editing in preview. My default PDF editor/viewer is preview. I'm unsure if the latest update caused the issue or the timing is merely coincidental. I hope someone can help. Thank you.