Question: I don't like the feature that automatically detects faces in Photos for OS X because of the unnecessary CPU and disk space consumption. A photo library of 360 MB generated 50 MB of face detection data inside the Photos Library.

Is there any way to disable this feature in Photos for OS X?

Answer: 
There is a way to do this now in Photos Version 3.0 (3271.13.150).

In the sidebar select People. Then select all the faces that show up and right click. There is an option to delete/reset all saved face data.
You can find the option in **View > Hide Face Names**.