James,
Photo album does this. Can you tell me what performance problems you think would occur? If you use the filesystem storage method, all the actual image data is stored on the filesystem.
The latest cr_write_content uses ns_returnfile which will cache the data if you have fastpath enabled. (I am not sure of the details of this, but sounds like it could be helpful).
I assume if you have millions of products that your store will have more millions of orders than photos.
You can look at the photo-album package. It creates a cr_item for a photo, and one cr_item for each image size. I believe is has a thumbnail, medium and full size image for each.
Dave
