Truenas core - zpool import - 100% single core usage for days

I tried to repaireimport a pool out of 4x8TB which is importable readonly and obviously has some broken snapshots within.
zpool import -F -n zpool3-1
and also via
zpool import -F -n -N -X zpool3-1

But nothing happens inside 2 days except immediately increased Processor usage (AMD Ryzen 5 PRO 4650G). 1 core goes up to 100% but its not visible in top or htop.

Truenas core - TrueNAS-13.0-U6.2

image