Performance in regard to compression is actually extremely good on ZFS. It's performance in other areas where it has problems, especially when it comes to NFS. I can appreciate not wanting to use it in this case. You do have to take a hit in performance if you want to run VMs over NFS, however I've used ZFS enough to realise that I'm willing to put up with this in order to get its other features (and you can alleviate it a bit using decent SSDs).
I'm not aware of any way of doing compression on any other FreeBSD file system (read UFS). You'd want a compression GEOM module, which would be a very interesting addition to the GEOM stack, but I'm not aware of it existing anywhere.