@andrewplested ha ha! Do you need to get it under 10 MB? Colorsync Utility on Mac can work wonders if you're looking for an alternative.
There is also a ghostscript command line for different pdf compression levels.
gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/screen -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf
where "screen" is probably too compressed. Alternatives are "ebook", "printer", "prepress". (It may be possible to bump the CompatibilityLevel to 1.5). Not very fine-grained, but it can compress *a lot* and all elements are compressed consistently for the output
@BorisBarbour @steveroyle @andrewplested a couple of other options I used in the past (these work on Linux, not sure about Mac sorry).
Depending on how the PDF was generated some work better than others
1. use pdftk
pdftk inputfile.pdf -o outputfile.pdf compress
2. convert to postscript then back to pdf
pdf2ps inputfile.pdf output.ps
ps2pdf output.ps inputfile_small.pdf
3. use qpdf
qpdf --linearize inputfile.pdf output.pdf
