Unlike 7zip or RAR, CHDs do not need to be unzipped to play. Most modern emulators (DuckStation, PCSX2, Flycast) read them directly, meaning zero extra load time. Command-Line Native:

If you are compressing PlayStation 2 or Sega Saturn images, the difference between a 2016 chdman and the 2026 version is the difference between "game crashes at cutscene" and "game runs perfectly."