Zcash NU7 upgrade aims to cut block times while preserving halvings

Zcash developers are targeting Nov. 5 to activate NU7, the network’s next major upgrade. NU7 is set to reduce the time between confirmed transaction batches from 75 seconds to 25 seconds. Developer Sean Bowe said NU7 will reach Zcash’s testnet on Oct. 6, and the team will set the final mainnet activation height on Oct. 20 after observing the network under the new rules. The Zcash Foundation, Project Tachyon, Valar Group, ZODL and Shielded Labs reached what developers called unanimous agreement on the upgrade’s scope and timeline. The underlying specifications are due by Sept. 30. The shorter blocks would normally produce roughly three times more blocks and new coins per day. ZIP 218, the proposal included in NU7, would reduce the reward per block by roughly three so that total issuance per unit of wall-clock time remains where it was, according to the specification. NU7 also includes a Network Sustainability Mechanism that will set aside roughly 60% of transaction fees beginning in 2026. Those banked fees are scheduled to return as supplemental mining rewards in February 2031. The five development teams called that date the most conservative reading of the coinholder vote. Zcash coinholders voted to keep the network’s Bitcoin-style halvings, which reduce mining rewards by half every few years until issuance approaches zero. The vote recorded 2.4 million ZEC, or 66% of the eligible pool, and 98.9% of votes cast supported retaining the model. The upgrade is not expected to require major wallet changes, and it does not add new transaction types. Zcash uses zero-knowledge proofs to validate payments without revealing who sent them, who received them or the amount. In July, the network activated the Ironwood upgrade to patch a four-year-old flaw that could have allowed counterfeit ZEC to be minted; the scare briefly drove the token down 38%. ZEC has since risen more than 2,500% over the past year, with the article citing Ironwood’s fix and Grayscale’s listing of a spot ETF as factors. The ETF trades on a regular stock exchange and tracks an asset’s price, allowing investors to gain exposure without directly holding the coin.