The largest file is about 400kb (currently), I have included up to 47 images in my survey in testing.
When I load my survey on my iPhone, it works fine at both 200x200 dpi (400kb)per image and 600x600 dpi (1.5mb) per image. And when I have 12, 25 and 47 images. No issues basically.
When I load my survey on my large iPad, it works fine when the images are 200x200dpi quality and crashes when they are 300x300 dpi & 600x600 dpi. Quantity of images does not matter. When it does crash it only crashes when I try to open the group at higher image qualities.
When I load my survey on my mini iPad, it crashes even before the survey can load when image quality is at 300x300 or greater at any image quantity. When I use 200x200 dpi images with 12 images, it crashes when I try click on the group toggle show/hide.
This is my work around for including PDF attachments in my survey for user instructions.
This is confusing and I can clarify any questions.