In the past, I've used pdf2ps to convert the PDF to a PostScript file, then used ps2pdf to convert it back to a PDF. This often reduces the file size substantia

In the past, I've used pdf2ps to convert the PDF to a PostScript file, then used ps2pdf to convert it back to a PDF. This often reduces the file size substantially. I probably wouldn't recommend doing this for anything serious (since it might negatively affect the a11y of the file), but in the right situations it can be a quick and simple way to massively reduce a PDF's filesize without noticeable side-effects.