Wow - they must be pretty long lists - that would be about 4.5 gigs of MP3's per list - that could be many hundreds of files in each playlist. Well, there's only one way for you to find out if reducing that number would make a difference...
Create some additional playlists and drag the files from your existing lists into them. You will then need to delete the files from the previous list (only delete the entry - do not delete the file from the hard disk). Since you only have 9 lists currently, try creating an additional 27 lists (just give them temporary names for now) and then put one quarter of the files from each of your current lists into the new ones. And then try another sync. Since the MP3 data is already on the DMS the tame taken should only relate to the database changes. If the sync time scales badly with the length of the lists you should see some improvement. If so, then you can extend the principle further to create some more playlists. If it makes absolutely no difference, it's easy enough to drag the files back again and delete the temporary lists.
Just one thought - you mentioned books - how many files in each of them? Some audio books use many CD tracks per chapter. I have often found it better to combine these into a single file per chapter just to reduce the number of files.
