file size!!

Can you Package the brochure and share it via Dropbox or your CC account?

First: thank you all for your suggestions!

The problem was with the tiffs. I tested it by duplicating one page and converted all the photos to png´s. Then saved the identic pages as pdf, one with tiffs, one with png´s and...tataaa. The tiff one was 20!! MB and the png one was 230!! kB

The reason why I saved my pictures in as tiff files was that my project is going to be printed. And for the print it has to be in CMYK. png files cannot be saved in CMYK mode. Is it ok to use pngs? When exporting as PDF will they be converted?

Thank a lot!

Saving as Smallest Size PDF should reduce the size of the PDF.

Did you tick the option to Crop Data to Frames.

Just the bottom right one in the screengrab.

One other thing to check in the Links panel, is the Effective PPI of each image which should be around 300–400PPI, if they are significantly larger, resize them in Photoshop.

TIFFs are large and the difference in quality IMO is imperceptible. Try native PSD or compressed (to 8 or 10) JPGs, you'll see a great saving.

Did you look at the total size of your image files? Certainly, it's usually the images which add most of the size. But you can find out with Acrobat Pro. 

Go to File > Save as Other > Optimized PDF.

DO NOT SAVE.

Instead, use the Audit Space Usage button.

You can post a screen shot of what this shows, if you'd like us to explain some of it.