Zcash NU7 turns 75-second blocks into 25-second ones—privacy leaves the slow lane

Zcash developers have agreed to activate the NU7 upgrade at block 3,543,405, expected around Nov. 5, which would triple payment speed by cutting the time between blocks from 75 seconds to 25 seconds. The chosen height must still be merged into the deployment specification and included in node software before the upgrade can take effect.

Zcash developer Sean Bowe filed a proposal on Tuesday to set activation at block 3,543,405, a height agreed at a meeting of Zcash Improvement Proposal (ZIP) editors, the group that signs off on changes to the blockchain’s rules. The proposal had two approvals but had yet to be merged into the deployment specification as of 08:00 UTC Wednesday, when the specification still listed the mainnet activation height as undecided. Zakura’s public upgrade dashboard lists block 3,543,405 as the planned mainnet activation point, and node software must also include the chosen height. NU7 has run on Zcash’s test network since early October.

For an exchange that waits for three confirmations before crediting a ZEC deposit, the shorter block time could cut the wait from nearly four minutes to about a minute and a quarter, or 75 seconds.

NU7 will also temporarily remove 60% of the fees collected in each block from circulation. Those coins will be paid back to miners starting around February 2031, while Zcash’s existing schedule for reducing mining rewards by 50% remains in place.

The upgrade will shut down Zcash’s original Sprout privacy system entirely. Coins still in Sprout when NU7 activates will become unspendable, so holders have until activation in early November to move them.