Make sure Windows is totally up to date, including any parts of it you may never use (IE11 for instance - the McAfee User Iinterface uses it), then try running the Virtual Technician to see if it finds and fixes anything: http://mvt.mcafee.com/
Also check to see if you have any rival software still installed as it could be interfering.
Moved to Consumer > General.
thank you for your advice. unfortunately not working for me. still high usage.
- I have installed all window Important Update (including IE and NET framework)
- run MVT = found nothing wrong
- I only have CCleaner and Malwarebytes (both are rarely used)
i googled and found related discussion suggest to reinstall McAfee but afraid to do so
I would contact Technical Support for their advice.
Meanwhile make sure that Malwarebytes is not using active protection.
See "Contact Support here: Consumer Technical Support (alter Country @ top right as needed)