Version 3.9.3 was specifically optimized to handle the major under-the-hood shifts in Apple's file system:
Before the app evolved into the more complex CleanMyMac X, the 3.9.3 version was praised for its balance of utility and speed: CleanMyMac 3.9.3
you are using (e.g., MacBook Pro 2015, iMac 2020)? Which macOS version is currently installed? CleanMyMac - App Store - Apple Version 3
It offered "deep cleaning" tasks like reindexing Spotlight and repairing disk permissions to fix common OS slowdowns. Why People Still Talk About It Why People Still Talk About It It resolved
It resolved critical crashes and UI glitches that occurred when the older CleanMyMac 3 architecture met High Sierra’s new security layers.
For users with mid-2010s MacBooks that max out at High Sierra or Mojave, this version is often the most stable performance optimizer available.