@pertho @thesaigoneer First of all, the Btrfs snapshot creation and destruction activity seems to be more intensive than ZFS. I haven't measured it, but while ZFS keeps CPU usage low, Btrfs puts a noticeable load on the CPU.
I'm also fairly convinced that it is checking for updates, running systemd-related tasks, and so on. It's more automated, but that’s not something I need.