I am having the same problems as the OP ... but version 1.8k

Similar setup .. 2 PC's running 1 + 2/3/4 .. depending on if my little girl is playing or not.

The Performance Boost is ticked on both installs.

To be honest I never really looked for a stresser but it always seems to happen after a pause (Mute).

I did try to upgrade to v1.9g but got the dreaded message "LICENSE HAS EXPIRED". ;(

KeyClone ... I have sent you a PM with the relevent PayPal info as I am not sure of my email at the time of purchase, I was a little 8o spaced out due to medication.

I hasten to add that the medication was entirely legal and administered in hospital ..