Hi! A few weeks ago my early 2013 15" Retina started acting really slow. Not UI lag, just constant mini freezes, often with the beachball. Obviously, I checked the activity monitor, and everything seemed fine - 97% idle CPU, 1gb active RAM, 229GB free on the SSD. It got so bad that I can't use it. Here's what I've tried- Repairing Permissions Running disk utility first aid SMC Reset PRAM Reset Erased the drive and installed Lion Erased the drive again and reinstalled fresh OSX El Capitan Ran SSD Trim Enabler Nothing. Still slow. I figured I must have some sort of hardware issue, perhaps with the connection between the SSD and the logic board. I would replace the hard drive cable if it had one. Here's where it gets interesting- I installed OSX on an external HDD in an enclosure and boot from it, and it's reasonably quick. I've been living with this external HDD for weeks. Anyway, I run the blackmagic speed test on the SSD mounted as an 'external' drive, and I get good results. (200+MB/s) So I try booting from the SSD again, and it's slow still. I run the speed test while booted on the SSD, and it's painfully slow. (1-2mb/s) So I'm at a loss. It seems to not be a hardware issue, since the SSD was fast when tested as an external. It's only slow when booted from it. Is there any other steps to take? Thanks!