My previous post showed that my mini on El Capitan was using 3.6GB of ram freshly booted. I rebooted it a few times & it was the same. But then I changed some things: I had had two external hard drives connected before (that had already been indexed) so I dismounted them & unplugged their cables since I was suspicious of Spotlight. I also then turned off all notifications- all of them in the Notifications settings. Now my mini is using 1.41GB of RAM at idle with nothing launched and nothing compressed. Just regained 2.2 GB of RAM.