Not sure exactly what this is doing, but on my I7, I set "MixThreadCount" to 6, and Enable set threaded ideal processor to False, and my core #1 dropped from about 75% to about 10%.  It's actually lower than core#2 now.   Got to do more testing tonight.


OK! Now I'm getting someplace! :) "MixThreadCount" to 4 AND I had to set the Enable set threaded ideal processor to False. the cores  are spread-out better, I'm going to see if I can tweak this setting but it's grate as it now!!
Thanks Jim!      

Would this apply to i7 3770K (4 Cores) as well? or is it only 8 cores?
 

 
I'm one of those users that has to deal with this spiking first core, and I've seen so many others post about it. I'm really glad that someone has found an apparent solution/work-around. How exactly do I access that Configuration File and change the "MixThreadCount" and "Enable Set Threaded Ideal Processor" settings? Is this done from the settings menu in Sonar while it's launched, or do I have to get to it some other way? 

Preferences > Audio > Configuration File
Under Properties on the right

gustabo
Preferences > Audio > Configuration File
Under Properties on the right

Thank you. I will try this out when I get home from work. 

Eric,
 
If you have a quad core that does multi threading, you have in essence 8 logical cores.  You can tell in the performance window on how many CORE BARS show up.
 
Jim

Well, I am home and tried this, and while it took down the Core 1 spike, I am now getting nasty distortion and poor playback (even though nothing is spiking)
 

SilverBlueMedallion
Well, I am home and tried this, and while it took down the Core 1 spike, I am now getting nasty distortion and poor playback (even though nothing is spiking)
 

ASIO drivers?
Did you set the "Enable Set Threaded Ideal Processor" settings to false?
you may need to try different core numbers to get the best for you cpu.
Also you need to consider how much CPU your audio interface needs.

The really strange thing about this is that it's a relatively recent occurrence for me. It didn't used to happen at all. I always had a fairly even spread across all my cores according to the CPU Meter in Sonar. However, I rolled back to many of the other versions and tried opening a project in each one of them, and I still got similar spikes no matter what version I was using. I know that this issue wasn't happening before, but since it's still happening no matter what version I roll back to, it makes me think that there's some other issue going on with my system. 

skitch_84
The really strange thing about this is that it's a relatively recent occurrence for me. It didn't used to happen at all. I always had a fairly even spread across all my cores according to the CPU Meter in Sonar. However, I rolled back to many of the other versions and tried opening a project in each one of them, and I still got similar spikes no matter what version I was using. I know that this issue wasn't happening before, but since it's still happening no matter what version I roll back to, it makes me think that there's some other issue going on with my system. 

Did you think about dialing back win 10 updates or reinstall your audio drivers.? Those updates can sneak up on you.