FastPictureViewer is described as 'Award-winning image viewer for the Windows platform, specifically Windows 7, Windows Vista and Windows XP. It was designed and developed in Geneva, Switzerland by Axel Rietschin, building upon 15+ years of experience in industrial imaging software' and is a Image Viewer in the photos & graphics category. There are more than 100 alternatives to FastPictureViewer for a variety of platforms, including Windows, Mac, Linux, iPhone and iPad apps. The best FastPictureViewer alternative is IrfanView. It's not free, so if you're looking for a free alternative, you could try IrfanView or XnView MP. Other great apps like FastPictureViewer are nomacs, FastStone Image Viewer, XnView Classic and Adobe Lightroom.
with fastpictureviewer you can fast (one click) view and rate (e.g. flag for further purposes) the Pictures. MS Photos is nice to view some photos - but thousands ??