When inserting images into a pdf file (each image in a different page) it is quite easy to browse the images. Why when merging the same images with imagemagick (thus, creating a very large image file) is gets very slow to view the same content? Does JPG compression has something to do with this?
Probably it is because in PDF files, only the contents of the current page are in memory (maybe the last or next page depending on zoom factor). In image viewers, because they assume image files are small, they load all the file into memory, so when a really big image is chosen, maybe that image is fully loaded into memory, thus causing slow processing.