Zcash activates NU7, cutting target blocks to 25 seconds

At block 3,543,405, Zcash activated its NU7 network upgrade, according to CoinDesk’s report. NU7 cuts the target time between blocks from 75 seconds to 25, making the planned wait for a first confirmation three times shorter.

The block was mined at 02:34 UTC on Nov. 6, CoinDesk reported. Actual block times were still adjusting after activation, and exchanges set their own rules for how many confirmations they require before crediting a payment.

How could shorter blocks affect private payments?

NU7 sets block spacing at 25 seconds and adds limits on private transaction activity in each block. The limits reduce how much data wallets may need to download while scanning for payments.

Zcash Foundation said the changes more than double the potential capacity for Orchard transactions, a type of privacy-protecting payment, from 2.9 to 6.6 transactions per second. CoinDesk reported that the upgrade’s limits also reduce the worst-case download burden on light wallets. Actual transaction speed and service availability depend on network conditions and wallet or exchange policies.

What else changes under NU7?

The upgrade sends 60% of each block’s transaction fees to a reserve for future block rewards; miners keep the other 40%, according to the Zcash Foundation’s Zebra 7.0.0 release notes. The foundation says the reserve is scheduled to start returning to rewards at block 8,939,664, while the 21 million ZEC supply cap remains unchanged.

NU7 also disables version 4 transactions. The Foundation says funds remaining in Zcash’s original Sprout pool become unspendable because they rely on that format.

The next milestone to watch is the reserve’s scheduled return to block rewards at height 8,939,664, expected around February 2031.

Sources and documents

• CoinDesk’s report — coindesk.com
• Zcash Foundation’s Zebra 7.0.0 release notes — zfnd.org