I receive some PDF files with massive fonts (e.g. Arial Unicode MS) which bloat the file size by >20 MB.
Can I use PDFTron Optimizer (http://www.pdftron.com/pdfnet/samplecode.html#Optimizer) to shrink these files? I would like only to keep the glyphs that are acutally used in the document.
Yup, you can do this with SubsetFonts(true) in Optimizer.TextSettings.
This is shown in the following code snippet (in VB other languages are basically the same apart from syntax differences):
Dim optTextsettings As New Optimizer.TextSettings
Dim optSettings As New Optimizer.OptimizerSettings