FreeBSD 12 Runs Refreshingly Easy On AMD Ryzen 9 3900X - Benchmarks Against Ubuntu 18.04 LTS
For the common SQLite use-cases, Ubuntu with EXT4 was faster than FreeBSD with ZFS, though this isn't anything Zen 2 specific.
Though in the BlogBench read benchmark, FreeBSD did come out significantly faster than Ubuntu.
For the most part the results comparatively are what we've seen out of other Intel and AMD boxes when comparing FreeBSD to different Linux distributions.