"PDF Flattener ( pdftron.PDF.Flattener) can be used to speed-up PDF rendering on mobile devices and on the Web.
PDF documents can frequently contain very complex page description (e.g. thousands of paths, different shadings, color spaces, blend modes, large images etc.) that may not be suitable for interactive viewing on mobile devices.
Flattener can be used to speed-up PDF rendering on mobile devices and on the Web by simplifying page content (e.g. flattening complex graphics into images) while maintaining vector text whenever possible.
A quick way to try Flattener is by using DocPub CLI (e.g. docpub -f pdf my.pdf). If you prefer working with code, please take a look at the last code snippet in the Optimizer sample (which is included part of PDFNet SDK)."