Personally I would just avoid CPU mining unless you don't have to pay for the electricity, it introduces a bunch of extra power usage and heat for little added MH/s, bringing down your profitability (assuming you do pay for electricity). In my case it went so far as that the added heat from CPU mining caused my GPU's to throttle to the point where I had a better MH/s yield and less heat (issues) by just leaving the CPU alone. But that doesn't fix the problem of course.