we added thumbnail pictures to our blog posts which are of course also shown on the archive pages of the categories. The problem is that our archive pages massivly increased in page size because the thumbnail pictures are loaded in full size, not the size of the thumbnail itself. I can understand that this may be neccessary for the lightbox feature but we disabled it in the themes options. The images are still loaded ion full size.
Is there a way that the post thumbnail pictures are only loaded in the size needed for the thumbnail on archive pages?