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Zcash activates NU7, cutting target block time to 25 seconds

Zcash activated NU7 at block 3,543,405, cutting target blocks to 25 seconds and expanding shielded capacity while keeping issuance and its 21 million ZEC cap intact.

Uruguay Can Editorial

Zcash activates NU7, cutting target block time to 25 seconds

Zcash activated its NU7 upgrade on Nov. 6, changing a network that targeted a new block every 75 seconds to one targeting 25 seconds, which can shorten waits for private payments. The upgrade went live at block 3,543,405 at 02:34 UTC, according to CoinDesk’s report on the activation. The target interval is faster, though actual block times were still adjusting in the hours after launch.

How much more private payment capacity does NU7 add?

NU7 more than doubles the specified capacity for Orchard transactions, one of Zcash’s shielded formats, from 2.9 to 6.6 transactions per second, according to the Zcash Foundation’s Zebra 7.0.0 release notes. The upgrade sets per-block limits on shielded activity, which also constrain how much data a wallet may need to scan to find incoming payments. The Foundation says those limits cut worst-case sync bandwidth that a spammer could impose on light wallets by about 37%.

For you as a user, a quicker first confirmation does not guarantee that every payment becomes spendable sooner: merchants, exchanges and other services set their own confirmation requirements. The Foundation says the daily amount of ZEC issued stays the same because rewards per block fall as blocks arrive more often, and the halving intervals are adjusted to match.

What happens to Zcash transaction fees?

NU7 also begins the Network Sustainability Mechanism: miners keep 40% of each block’s transaction fees, while 60% goes into a reserve for future block rewards. The Foundation says reserve reissuance is scheduled to start at block 8,939,664; it also says the change preserves the 21 million ZEC supply cap.

Which older Zcash funds are affected?

Version 4 transactions are no longer valid after activation, and Sprout, Zcash’s original shielded pool, can only use that transaction format. Funds left there are therefore unspendable under NU7. CoinDesk reported about 12,224 ZEC remained in Sprout at activation, while a possible recovery mechanism had not been approved.

Sources