@Sawatakashi I can't get you a far advanced response, but basically yes, you'll have to go C++ and probably a SIMD integration regarding the efficiency.
But yeah that's probably how I'd do it, not knowing if there's a better (and accessible) method.
Since a C++ node gives you access to Hise API, Juce API, and any third party library you'll want to import, Hise won't be the bottleneck.