Are you embedding the .psd image file into Illustrator or linking it? You can look in the links panel to help determine this. If there is a small white “graphic” icon next to the name of your .psd image then it is embedded and all of the image data has been transferred to the Illustrator file. You could unembed the file via the flyout menu and the illustrator file will be smaller but you’ll still have the burden of having to manage the photoshop file and the illustrator file when sharing or printing your artwork.
Are you using the .psd file multiple times in the Illustrator file? If so, converting it to a symbol and duplicating the symbol throughout your page instead of multiple copies of the original will also help decrease the size of the file.
Lastly, can you decrease the size of the Photoshop file?
Hope there is information here that is useful to you.
Michael Riordan
Owner/Adobe Certified Instructor
Digital DesignLab
Oak Park, IL
http://www.learnadobesoftware.com