Pandora Image Viewer (PIV) by Jon Sneyers is a simple and fast image viewer.
Features:
– 4 times faster than other viewers, feels very snappy
– full 24-bit color
– zoom from fit-to-screen (up to 1:8) to 4:1
– nubs to pan around (left nub=fast, right nub=precise)
– supports JPEG, PNG, WebP, BMP, PNM (PPM/PGM/PBM), XPM, LBM, PCX, GIF, TGA, and TIFF file formats.