Problem with exporting large file at coreldraw x7

Hello people,

I always have a problem when i export files from cdr to pdf. I have a file at 160 mb and when i export to pdf everytime it stack. I have close all the text to curves and nothing happend, and at the end i convert the file to bitmap so i can export to pdf. But again it delayed veru much and the line at down and right side of the screen that sow aw that is savingit stay still at the middle. Even when i export pdf for web so it will be a small file i have the same problem. I also have a promblem when i make a catalogue and the size is big again. I forget to tell you that i import photos saved as png, at 300 dpi, (at png because i have crop them at photoshop). I also import photos saved aw tiff at 300dpi. Always at 300 dpi. Did i must save the photos at smaller dpi to reduse the size? Any answer it will be usefull