The embedded type PDF viewer or PDF Flipbook is the basic and default viewer from DearPDF. These are great to have on-page where the main page about the book or there needs a single PDF to display on the whole page.
Example: Embedded Viewer in a Page
But things change when there are more than one PDF document to display in a single page. A single Embedded viewer or PDF Flipbook consume certain amount of time to load and consumes memory. Thus multiple embedded viewers will increase that page load time and memory consumption additively.
So, we recommend using Lightboxes(Popups) shortcode solutions like buttons, thumbs, links.