I normally insert into Microsoft Word about 50 high resolution images and type notes above and below them. > Then export the file to save as PDF. > In this manner I am able to share over half a Gigabyte of images in a file less than 10 megabytes. I failed to achieve similar results in LibreOffice Writer running on Ubuntu Linux. The Writer could not Export the ODT file to PDF file. > For both OSes I have 64Gb of Memory and 4 Core Xeon. Please advise as to what could have gone wrong??
Have you already tried to fiddle with the values in Tools → Options… → LibreOffice - Memory ?
The default values are quite low for your machine specs.
In the PDF options dialog, did you try Lossless compression and/or unchecking Reduce image resolution?