If you add a lot of multimedia content — such as photos and movies — to your presentation, your Keynote document might get very large.
There’s an easy way to reduce a Keynote document’s file size — by removing the unused parts of the media.
To reduce the size of a Keynote document:
After you’ve reduced the file size of your Keynote document and then saved it again, you won’t be able to restore the images to a larger size or access the unused parts of your media files. It’s a good idea to back up your presentation before using this feature.
To learn more, see “Reducing Image File Sizes” and “Reducing the Size of Media Files” in Keynote Help.