I changed the file system of my BX500 SSD to btrfs instead of ZFS. I then tested the performance by transferring a 50GB file. There were fluctuations in the transfer speed but it never completely halted like it did when was formatted as ZFS. The total transfer time was probably about cut in half. So I'm going to assume the issue has been mitigated.
My advice to anyone else to only use drives with good sustained write performance if using ZFS. Though I haven't confirmed yet whether that would also fix the issue on my system.
