I've come up with a strange obervation. When I render my songs (I usually do in 192k), they only seem to use up to 50% or close to when I look at my system monitor. renoise itself ofc shows 99.9% in its monitor while stuff is rendering. Yes, the PC/OS has capability of running 100%. It is a 6-core xeon, and I have disabled hyperthreading.
At first I thought it is maybe because renoise cannot spread the project's cpu load to use 100% all the time, but now for so many tracks I'm working on with many tracks/instruments, more than 3, I've found they all seem to only use up to 40-50% cpu while rendering. Load seems to be spread along the 6 cores more or less evenly. Maybe there is a bug involved keeping renoise from using full throttle? I would have supposed, in rendering mode renoise could use as much cpu power as it wanted, because it doesn't have to be in sync with a clock?
It is renoise 3.1.1 on an ubuntu system, using only native instruments and effects.