Depending on your signal routing, yes, it can be normal that you only use a fraction of your available cpu. That’s the nature of digital processing. It can some things in parallel, but not all things.
Thanks,
I’ve checked both normal and boost priority. On my setup it doesn’t make difference.
The plugins are regular set such as EQs and compressors: most instances of FabFIlter Q 3 (vst3) and some of soothe2 (1.1.0).
There is no plugin which is significantly more power consuming than others.