Samplitude uses too little CPU power for rendering the project. I have a 16 core processor and Samplitude only uses 18-20% of the power. I'm attaching a printscreen.
According to the printscreen, Samplitude also uses other cores. But probably not enough.
@XSOM In your screenshot it looks like that four cores are used for rendering and a another core is maybe used for the GUI. The two cores that go up and down in an alternating way probably need to wait for each other to finish some calculations or wait for the other cores. The bouncing process cannot be faster than the slowest sub-process.
What are your multicore settings in the system settings of Samplitude?
Maybe you get more cores if you render a surround sound project. I would guess calculating more audio channels would use more cores, one core for each channel.