Zcash NU7 upgrade implemented: the block interval was reduced to 25 seconds, and private payments were accelerated by 3 times
According to Woofun AI, the Zcash network officially implemented the landmark NU7 upgrade on Friday morning. The core change was to drastically reduce the block generation interval from 75 seconds to 25 seconds, making the confirmation efficiency of private payment transactions triple. The upgrade took effect in the 3,543,405 block unearthed at 02:34 UTC, marking Zcash's most significant performance iteration since it went live in 2016. The purpose of this adjustment is to solve the pain point of slow confirmation of private transactions, and to provide an almost real-time settlement experience for daily consumption, exchange deposits, and cross-chain transfers through a more intensive block generation rhythm, thereby reshaping the competitiveness of privacy coins in mainstream payment scenarios.
From a technical perspective, increasing the frequency of block generation poses a serious challenge to the network's ability to synchronize. When miners discover new blocks, the entire network needs to complete reception and verification before starting the next round of competition. Shorter intervals mean that the time window left for miners to catch up is drastically reduced, which can easily lead to forks and block abandonment. In response to this risk, Zakura, a node software developed by Valar Group and Project Tachyon, conducted intense stress tests on 80 computers distributed across 11 regions.
According to data compiled by Woofun AI, the block abandonment rate in the 25-second interval mode is only 3.43% under strict conditions where each block contains multiple transactions, which is slightly higher than 1.57% in the previous 75-second interval, but it is within a manageable range. By introducing an incremental verification mechanism, Zakura performs partial verification and caches the results when the transaction first arrives, avoiding repeated calculation after the transaction is inserted into the block, and only re-executes the process that relies on the latest account balance and history records, thus maintaining network stability while improving throughput.
The NU7 upgrade also introduced hard limits on private transaction capacity to balance network load with the processing pressure on users' wallets. Since private wallets need to scan the entire chain to match their own payment information, mass transactions can cause all nodes to bear too much computational burden. The new regulations reduced daily data downloads from 271 megabytes to 169 megabytes in the worst cases, effectively reducing resource consumption. Combined with more frequent block generation, the processing capacity for simple private payments is expected to increase from around 3 transactions per second to more than 6 transactions per second. In the application scenario, merchants only need to wait about 25 seconds to obtain the first confirmation, while exchanges that require three confirmations can reduce the waiting time from nearly four minutes to about 75 seconds, significantly improving capital flow efficiency.
Furthermore, the fee allocation mechanism has fundamentally changed: according to the distribution rules of ZIP 235, miners only keep 40% of the handling fee, and the remaining 60% is removed from circulation and recorded in reserves. It has been accumulated since block 8,939,664, and is scheduled to be used to distribute block rewards starting in February 2031. This is a network sustainability mechanism (NSM) proposed by Shielded Labs to ensure that the 21 million Zcash supply cap is not breached. In line with this, ZIP 237 lowered the reward per block to one-third of the original, so while block production was accelerated by three times, the daily circulation volume remained the same.
With the full implementation of NU7, Sprout, the original privacy protection mechanism used by Zcash since 2016, was officially abandoned, causing approximately 12,224 ZECs to temporarily lose their transfer channels. Co-founder Sean Bowie has proposed a potential recovery plan, but as of Friday, it has not been approved by the community; the agreement layer reserves the possibility of future upgrades and restoration, while not ruling out that it will never be opened again. The fate of this part of the asset is still undecided. In the long run, NU7 sacrifices part of the theoretical decentralized redundancy (higher abandonment rate) in exchange for extremely high utility and throughput, which is a key step in the private chain towards large-scale application.
This upgrade not only strengthens Zcash's technical barriers in the field of private payments, but also provides a reference paradigm for performance optimization for other privacy-focused blockchain projects, which indicates that private transactions are moving from edge experiments to efficient everyday applications.