Illustrator Extremely Slow With Linked Photos

I am creating some large banners at my job, and using Illustrator to create specifically shaped clipping masks. The problem is, this file is getting way too large and slow. I am trying to figure out how to convert this to an InDesign document, but not coming up with very good methods to import the clipping mask / crop boxes over. I should have made this originally in InDesign, but didn't think Illustrator would run this slow (not on the best machine).

Any ideas?