If you are looking to replicate this experience on a modern PC, users typically recommend downloading the open-source ImageGlass or restoring the legacy Windows Photo Viewer via registry edits, as the modern "Microsoft Photos" app is significantly different in function and feel.
The defining characteristic of Photo Viewer was its speed. In 2010, computer hardware was transitioning from single-core to multi-core processors. Photo Viewer opened JPEGs, PNGs, TIFFs, and GIFs instantly. It required a fraction of the system resources that modern apps like the Windows 11 "Photos" app require. There were no splash screens, no "Preparing your experience" loading bars—just an image on the screen. microsoft photo viewer 2010
Many found the UI less intuitive than the simple 2010 layout. If you are looking to replicate this experience
: Displays all stored photos in a selected folder as small previews. Photo Viewer opened JPEGs, PNGs, TIFFs, and GIFs instantly