Thanks. Have changed settings and am installing atop. Let’s see what happens.
I installed atop and was able to track down the problem.
Seemed that the dkim-mil filter and SASLAUTHD were out of control and the dkim file was around 1GB and was using 100% CPU. Seemed to have spawned an entire city of processes (150+). Still not sure why. I stopped the service uninstalled and re-installed both programs and so far, so good.
The other program that was using 100% of CPU for 20 minutes at a time was bw.pl (bandwidth monitoring) which I didn’t really need so I turned that service off.
Good to hear you found the issue! You see, atop really helps in such cases. Also for me it has helped greatly in the past when nailing down processes running rampant. 