Уменьшение размера PDF-файлв.

документация

Т.е. при вызове gs можно указать опцию -dPDFSETTINGS=configuration, где configuration может быть:

/screen selects low-resolution output similar to the Acrobat Distiller (up to version X) “Screen Optimized” setting.

/ebook selects medium-resolution output similar to the Acrobat Distiller (up to version X) “eBook” setting.

/printer selects output similar to the Acrobat Distiller “Print Optimized” (up to version X) setting.

/prepress selects output similar to Acrobat Distiller “Prepress Optimized” (up to version X) setting.

/default selects output intended to be useful across a wide variety of uses, possibly at the expense of a larger output file.

На этой же странице чуть ниже про создание PDF

Ну и собираем всё вместе:

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.3 -sColorConversionStrategy=UseDeviceIndependentColor -dPDFSETTINGS=/ebook -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

Tracedump:

newBaseSize: 16pt
newBaseSizeInPt: 16