Or only from individual core score? These specs are always too general.
Yes Pianoteq takes full advantage of additional cores, but also yes, it's not so obvious what's going on.
I'm running Pianoteq on the Odroid N2+ where I can assign the 6 cores to Pianoteq and I was able to play around with the core assignments to get a better idea of how it worked. For reference, the N2+ has 6x cores: 2x low-performance and 4x high-performance cores. Here's what I found out.
Assigning Pianoteq to a single core.
The Pianoteq performance index reflects the performance of a single core
. It doesn't matter if I assign Pianoteq to 1 or all cores, I get the same Performance Index number. In the case of the N2+ if I assign Pianoteq to 1 of the low-performance cores I get a ptq index of 20, and for a high-performance core 34 (38 if overclocked). If I assign Pianoteq to all 6 cores, the ptq index will show 20...34. You may also see dual ptq indexes on computers with hyper-threading, with the virtual hyper-threaded cores showing a lower ptq index.
Assigning Pianoteq to more cores will do two things:
1. It will stabilize/peg the Pianoteq Index (blue line) to the top of the graph so it doesn't fluctuate. The blue line represents the CPU power available to Pianoteq. You want this blue line pegged to the top of the graph - and you can get that by either assigning more cores to Pianoteq or getting rid of unnecessary background processes that eat CPU cycles. If you see wide fluctuation in the blue line, this means that the estimated available CPU power / overhead is being used up by other programs. Mainly you don't want the blue PTQ index to drop below the audio load (orange graph) - causing dropouts.
2. Extra cores will also help keep the orange audio load graph in check when there are spikes in CPU usage (e.g. lots of notes/sustain/bass/dynamics etc.). When I'm only running PTQ on 1 core, the orange audio load will easily spike under normal conditions causing cpu overload/dropouts - and by spike I mean the orange graph will spike above the blue ptq index line. But when I assign Pianoteq to more cores, it is able to do a better job of keep the orange audio load graph from spiking - even if I'm forcing the dynamics, sustain polyphony etc. For example, on the N2+, using 1 high-performance core, it will easily spike at polyphony of around 32-64. With 4x cores I can easily push the polyphony up to 128++ without any dropouts/cpu overloads - the orange audio graph will easily stay low and level.
ARM little.BIG cores
On some ARM computers with little.BIG cores (low and high performance cores) - the audio load and ptq index blue line can become very fragile/brittle when the OS switches between the low and high performance cores. It results in the blue line fluctuating and the orange audio load graph quickly spiking. On those computers where this is a problem - it helps to assign just the high-performance cores to Pianoteq and leave the low-performance cores for the OS.
How many cores is the limit?
I'm not sure how many cores are the point of diminishing returns. I can tell you that on the N2+ with 6 cores, Pianoteq will utilize all the cores. On the system monitor (htop) - I can see the main Pianoteq application has a single dedicated thread on 1x core and then 1-2 child audio threads assigned to each of the other cores
Keep in mind that the Raspberry Pi and N2+ are at the bottom of the Pianoteq CPU threshold (so it's a good place to see the results of using more cores). But even my old dual core 2015 MacBook Air has more than enough single-core power to easily handle anything I can throw at it without any issues on playback.