DSP Robotics Support

Hi guys. I want to make modulation of the pitch in a wide range and keep the detuning from osc plus calculate pitch mod each sample. But for this you need (maybe I'm wrong) to use power function, a look other synth like Spire It looks like he counts every sample. But how does he do it? If I use the function each sample is a big CPU load.
I played a little and tried to come up with something, but what I got sounds linear. How can I modulate by + - 8 octaves without using a power function in the stream?

Apply your modulation source to the pitch, then convert to frequency (0-1) to drive your oscillator You don't have to do the conversion at sample rate, try hop(64).