FastDMG is a utility to mount .dmg and other disk images quickly, without any unneeded nonsense. It is a fast and reliable replacement for Apple's DiskImageMounter.
Doesn't waste your precious time verifying disk images
Auto-accepts annoying end user license agreements
Runs in the background (doesn't show up in the Dock)
Displays no windows or menus and stays out of your way
Multithreaded, can concurrently mount several images
Disk image document icons continue to look the same
Handles all disk image types supported by DiskImageMounter (dmg, iso, smi, etc.)
What’s new in version 1.0.2
Updated on Feb 02 2021
Version 1.0.2:
App is now built as a Universal ARM/Intel 64-bit binary
I have not tested it yet, but I'm very interested as sometimes DiskImageMounter fails to mount images that I know are good, for mysterious reasons while Disk Utility mounts them ok...