Originally Posted by Eric
I think this is due to some of the merchants blocking the script from downloading the images.
That's because all of the tags in your views are calling the image files and not the thumbnail files.
It could be related to what ayorofrance mentioned or due to the fact that the merchants are blocking access to the images.
I changed the image tags on your Category Pages to [product.thumbnail tag='1' direct='1'] and now your category pages load super fast with all images appearing. You might consider using this method to display the images throughout your site. I only edited 1 view (Category Page > Default > Product List) in your store.
Awesome! Thank you very much, Eric! Hopefully this will solve the issues. I'll be making those changes ASAP