HakView was created as an ultra-fast and ultra-small app to browse large numbers of pictures.
You can open pictures one-by-one, or open whole folders and browse all pictures using the arrow keys to move to the previous and next image. You can zoom images to full window and also display them in full screen. You can center them on screen. You can also display list of all images in the folder so you can see which image is currently displayed or browse them and open another image in the list.