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Spotlight gone wild - mdworker processes eating too much CPU on macOS

My macOS slowed down a lot recently, so I inspected all the running processes with the htop terminal command and I saw that 40-50% of CPU (on all cores) is eaten by mdworker processes.

Google search revealed that mdworker processes are actually the Spotlight app indexing my local disk files. How to prevent Spotlight from going wild?

  1. Go to System Preferences -> Spotlight
  2. Uncheck all the categories that you don't want Spotlight to index / search through (in my case, I unchecked everything except for Applications and System Preferences)
  3. Voilà, the CPU drops right away. The mdworkers won't be indexing my disk anymore.

Note: Alternatively, you can inspect processes using top terminal command or with the Activity Monitor app, both shipped with macOS.

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