Remove all those fonts, you aren't using any of them.
One of them alone is 22MB.
That will drop the book down to 1.2MB instead of 17MB which should help tremendously.
EDIT: That might be because, as DomesticExtremis points out below,
nofew styles are in use... only the auto-generated styles for the ToC are in use.
Still, do you
really need to embed arial specifically? Embedded fonts are something IMO to be used as a last resort.