The high CPU usage happens at every restart and/or wake up from sleep.
The state is continue for approximately 10 minutes or more.
Disable Windows Defender does not help.
Avast rc 12.3.2278 does not help too.
Note. I always use avastclear.exe before install Avast.
ENVIRONMENT:
Host machine : Windows10RS1 + Avast Free 12.2.2276 <--- no problem
Core2Quad@2.5GHz+MEM8GB
Guest machine : Windows10IPbuild1607 + Avast Free 12.2.2276 <--- the problem happens
Assigned 4CPU+MEM3GB