How do I reduce the file size after merging PDF pages?

Q: When merging similar single page PDF files to a single multipage
PDF we end up having same font embedded for every page. This
unnesessary increases the size of the output file. We are looking for
ways to reduce the file size.

A: How are you merging PDFs together? The recommended approach is
using pdftron.PDF.PDFDoc.InsertPages() as shown in PDFPage sample:

2nd snippet in:

In case you are merging multiple files that have the same resource
(e.g. font, image, ICC profile) repeated over and over again, you
could use 'pdftron.PDF.Optimizer' (as shown in to eliminate
duplicates (to subset images, subset fonts etc) just before saving the
file. Acrobat Pro is by default running its own Optimizer when saving