I use the free built in Windows Defender for antivirus.  I've used it for years (when it was called Microsoft Security Essentials) and have not had any virus problems and it does not interfere with Sonar.  I had a problem years ago with either Vista or early Win 7 and an early version of Sonar.  Cakewalk support noted that the AV I was using was a known "potential" cause of my problems.  I switched to Microsoft Security Essentials and my Sonar problem went away.
 
When I run Sonar I always disable the Ethernet NIC (I don't disconnect the cable).  If you just disconnect the cable the Ethernet NIC and some programs will still be trying to access the Internet. 

Thanks Fireberd!  I was unaware of the concept of disconnecting the Ethernet NIC. 
 
I would really like for us to earn a "resolved" tag for this thread.  I'm going to uninstall McAfree now and install Avast.  It may take a day or two before I can gauge its elimination as having been the primary issue.  Fingers crossed.  Regardless of the outcome, all of the suggestions I applied from previous posts HAVE made a positive impact on my computers performance. 

Day 3 following removal of Mcafee with Avast taking its place and not a single audio engine failure or "sonar not responding" error.  CPU is running smooth and quickly as I had hoped it would when I upgraded.  Mcafee was not the only issue, but thanks to this forum I have successfully enhanced performance through a well orchestrated process of elimination.  All 3 previously mentioned days included the use of LatencyMon and I am stoked to say there were no issues reported!  Thanks EVERYONE who chimed in!  Im not sure how to check this thread as "solved," but that is its new status.

Awesome update to hear. Hopefully many happy days ahead as well.

If you edit the original post you can update the title of the thread.

mettelus
Awesome update to hear. Hopefully many happy days ahead as well.

If you edit the original post you can update the title of the thread.

Thanks Mettelus!  Your time on this project was much appreciated!  I will update the original post now.