Help please

I am still working with indd cs6 (own full suite, eventually will get CC) creating greeting cards and just cannot figure this out. Sorry if this is a bit long

I create vectors in illustrator but feel more comfortable designing in indd. I then bring vectors into indd and print them size as, say 5”x5”, which is no problem.

My problem is that I reduce each card to thumbnail size and create sort of a "small catalogue".

To make the thumbnails in indd, I have been grouping the vector and text of each card and then just scaling it down to approx 1”x1”. So approx 20 thumbnails/page and roughly 25-30 consecutive pages to be viewed online. My problem is that doing it this way the file ends up about 20-30MB, even if I save as lo res pdf.

to keep (catalogue) file size down to under 3MB, would the efficient way be to save the AI vectors as jpgs and just not use any vectors in indd? thanks!!!!!