NU7 reduces the block target time to 25 seconds while easing the workload for wallets scanning for private payments. The upgrade also sets aside a portion of transaction fees to reward future miners.
Early Friday saw the activation of Zcash’s NU7 upgrade, which slashes target block times from 75 seconds down to 25. The tweak allows private payments to confirm three times faster than before.
The network went live with the upgrade at block 3,543,405, which was mined at 02:34 UTC. According to ZecStats, another 225 blocks had been produced by 04:59 UTC, averaging around 39 seconds apart while mining difficulty continued adjusting toward the faster pace.
Zcash allows users to transfer funds while keeping the sender, recipient, and overall amount private. With these quicker confirmations, using those transactions at storefronts, on crypto exchanges, or when bridging assets between blockchains will be made significantly easier.
A merchant could typically spot a payment’s first confirmation in around 25 seconds. Meanwhile, an exchange requiring three separate confirmations will see its expected wait time cut from roughly four minutes down to just 75 seconds.
Because each service establishes its own rules, the speed with which customers can access their funds will also be shaped by the platform handling the transaction.
Keeping miners aligned at that rapid tempo required far more than simply adjusting the network clock.
How the System Works
Whenever a miner discovers a block, other miners must receive and verify it before beginning work on the subsequent one. During this lag, competing blocks can be produced by other nodes that the network eventually discards—and these tighter intervals leave far less time for nodes to sync.
Zakura—Zcash node software built by network developers Valar Group and Project Tachyon—tested 25-second blocks across 80 nodes in 11 regions, with every block packed with data. Under these heavy network conditions, 3.43% of mined blocks were discarded, compared to just 1.57% under the previous 75-second standard.
Network engineers also eliminated repetitive workload across the system. The software validates a transaction upon initial arrival and caches key verification steps so it doesn’t need to start over once that transaction is included in a block. Verification steps tied to the latest account balances and blockchain history are still executed again.
NU7 also caps the volume of private transaction data permitted in each block. Wallets have to scan the entire blockchain to detect incoming payments, so an attacker spamming the network could force every wallet into heavy processing work.
According to the upgrade specification, these limits drop the worst-case daily download burden from 271 megabytes to 169. Pair that with more frequent blocks, and the specification estimates capacity for simple private payments could more than double—jumping from roughly three per second to over six.
Transaction fees are also shifting under the new structure. Miners now receive 40% of all transaction fees, while the remaining 60% is pulled from circulation and locked into a reserve that will begin funding future block rewards around February 2031. This mechanism ensures Zcash maintains its hard cap of 21 million coins.
The NU7 upgrade officially retired Sprout, Zcash’s legacy 2016 privacy pool, leaving roughly 12,224 ZEC unspendable. A potential recovery plan was outlined by co-founder Sean Bowe, though network developers have yet to approve any solution.
