If you are looking for a basic image viewer without great pretensions, that is, that it is very small, that it does not consume resources and that its function is strictly to only visualize your images, then the answer is PictView.
PictView is just that, a very simple image viewer from which you can view all your photographs and be able to see them calmly in full screen. As usual in these types of programs, it allows you to select a folder full of images and shows them one after the other, allowing you to zoom in on the photo you want to enlarge it.
Ideal for those users who do not want to have large graphic programs installed and seek simplicity first and foremost.
You can free download PictView 32, 64 bit and safe install the latest trial or new full version for Windows 10 from the official site.