pdf_reducer

This module reduces the size of uploaded PDF files, to reduce the download time (UX) and the disk and network usage (sustainability). It's especially useful for mobile devices with low bandwidth.
This also improves the perceived performance of users' devices, thus reduces the incentive to change one's device, which is usually considered as the biggest contribution to the ecological footprint of the web.

It's one of the recommendations of the french General Ecodesign Guidelines for Digital Services (RGESN 5.7).
See also in french: https://www.greenit.fr/2013/03/06/eco-conception-web-optimiser-les-pdf/

Features

When a PDF is uploaded to a file field (also works in rich text editor through the Editor file module), this module uses a Ghostscript PHP library to reduce the PDF file to the "ebook" quality level, which is usually good enough.
In some cases, the compression fails or the resulting file is bigger. If so, it's not kept and the original file remains.
Otherwise, a message is shown to the uploading user to inform that the file has been reduced. In that case the original bigger file is not kept on the server, it's replaced with the compressed one.

Post-Installation

No configuration needed. All file fields will automatically get this feature as soon as you enable the module.

Additional Requirements

Be aware that Ghostscript has to be executable on your server for this to work.