Publish to PDF - File size problems

Good Morning - I have recently converted to X4 from ver. 12 and I am having problems when publishing to PDF with file size. Previously when using ver. 12 my PDF would rarely come out over 1MB in size now they are converting to between 3 and 12 MBs. Can anyone help me get these down to previous size. Most files I need to convert are for client approval and contain both bitmap and vector images. I need to keep the vector images vector and cannot present them as jpeg.

Any help would be great - thanks.

 

mike