https://www.theregister.co.uk/2018/01/17/zfs_performance_hit_by_spectre_meltdown_bug_fixes/

The widely used ZFS file system software is slowed down in both read IOPS and throughput by fixes for the Spectre and Meltdown bugs.

Systems engineer Jon Kensy blogged about the results of his ZFS testing, based on a VM running ZFS on a Ubuntu 16.04 LTS system on a Dell R620.