I just fixed all my problems with a few things.
do the following.
1- change disk pre load to 2 Seconds… try one second. after each change hit apply on each change.
2- disable the stupid auto record enable setting that creates havoc.
“Enable Record on Selected MIDI Track” found in “Preferences → Editing → Project & MixConsole”.
3- leave Asio guard on & change your buffer settings to find what works best.
4- With kontakt cores TRY OFF FIRST
Then follow the attachments.
Lastly I see the mac terminal hack, I have not tried this yet but seems to be really working for everyone.
terminal Hack
I still find cubase 8 a little buggy, even on a totally new system… just proves it’s not our computers and could be cubase?
regardless these small fixes really fixed up performance for me & a few friends machines as well.