I've been experiencing performance issues on my mid-2011 mac mini (running El Cap) for a while now -- beachballs, spotlight issues, general slowness -- and have been so far unable to discern the actual cause (this is, in part, why I haven't yet upgraded to Sierra). I just noticed that the root of my primary drive is marked as quarantined:
andy@Aurora[14:57:14]: $ ls -ldeO@ / drwxr-xr-x@ 40 root wheel - 1428 Jan 7 16:20 / com.apple.quarantine 68
Is it possible that this is the cause of my problems? And how would I go about fixing it?