jackd cpu usage when idle?

Hi list,

I am wondering why jackd does consume CPU cycles when idle, that is when
no software is accessing it, and hence keeps my laptop's fan spinning
the whole day. I can work around it by setting a rather high latency,
but am wondering what keeps it busy in general.

thanks for all ideas and hints!
Peter

PS: Does anyone know if the jackd emulation of pipewire uses less cpu when
idle than native jackd?