Fast Deduplication was developed by Klara Inc and iXsystems and offers up to x20 greater performance.

“With the introduction of Fast Dedup, there have been several major innovations including:

• The size of metadata is now dynamically sized to fit in either RAM or dedicated flash devices to avoid hitting the performance penalty wall.
• The metadata structure has been completely re-engineered to enable efficient updates using a log append process, greatly improving performance for large updates such as deletions.
• The dedup table will favor dedup-able data and prune blocks that show no dedup potential.
• Combining metadata improvements with properly configured storage, including dedicated metadata flash devices, will improve the sustained dedup performance by over an order of magnitude for larger systems.”

Some users are sceptical about potential data loss issues, as with any filesystem technologies..

https://www.ixsystems.com/blog/fast-dedup-is-a-valentines-gift-to-the-openzfs-and-truenas-communities