I had the same lag when I jumped to Nougatella .. went back to Marshmallow and the lag is gone. Considering the age of the tablet, I think I'll just keep it on Marshmallow till it hits the recycle shop. Is there a way to keep the Security patches ...
I had some initial trouble with the two ASIX 100MBit USB 2.0 adapters I have: They'd report an error while transferring large 2GB files from a CIFS mount, some sort of I/O problem from deep down in the driver stack that sounded very ominous.
I used this update (CARBON-KK-NIGHTLY-20141013-0952-n7000.zip) since yesterday and I haven't any issue or FC.
I used it from saturday evening without issue or FC. You could try it.
My N7000 is with 6.3. How I could find the Developper options and switching between Art or Dalvik, please ?