By default, in an opened PDF document, you can see the page thumbnail in the Pages panel in the Navigation pane. These page thumbnails are created on-the-fly whenever you open the Pages panel. For large documents, generating the page thumbnails can take several seconds.
Embedding page thumbnails into the document makes them appear faster, but increases the file size. Page thumbnails are not embedded by default. To embed page thumbnails, do as the following:
- Right-click any thumbnail and choose Embed All Page Thumbnails.
- Click OK in the pop-up message box.
- Save the file.