That it changes cores only when the window becomes invisible is likely due to App Nap - check the energy tab in Activity Monitor. https://developer.apple.com/l

That it changes cores only when the window becomes invisible is likely due to App Nap - check the energy tab in Activity Monitor. https://developer.apple.com/library/archive/documentation/Performance/Conceptual/power_efficiency_guidelines_osx/AppNap.html https://developer.apple.com/library/archive/documentation/Pe... https://developer.apple.com/library/archive/documentation/Performance/Conceptual/power_efficiency_guidelines_osx/PrioritizeWorkAtTheAppLevel.html#//apple_ref/doc/uid/TP40013929-CH36-SW3 https://developer.apple.com/library/archive/documentation/Pe...