Big beautiful imagery eats up alot of space in PPT, but there is a way to get large PPTs into more manageably-sized PDFs without giving up quality and resolution. Keep your PPT at full-size and use this trick to send your beautiful presentation to clients.
1. In PowerPoint go to File, Export
2. Under File Format select JPEG, and save every slide.
(Note: you may want to reduce the width down to 1500, as that will further reduce the final file size, but it may not always be necessary.)
3. Open Acrobat
4. In Acrobat, select File > Create > Combine Files into a Single PDF
5. Select Add Files (or drag & drop) the slide jpgs you created into the Acrobat Combine Files window
6. Select Combine Files (in the bottom right of the Acrobat window)
Acrobat will convert the jpg files, and then open up your new much more manageably sized PDF!