Zcash Slashes Block Times to 25 Seconds in NU7 Testnet Launch

Zcash has taken a major step forward with the activation of its NU7 network upgrade on the public testnet. The upgrade, which went live on October 4 at block height 4,465,026, introduces a significant change: block times have been reduced from 75 seconds to just 25 seconds. This adjustment aims to improve the efficiency of point-of-sale payments, exchange deposits, and cross-chain bridges, where longer wait times have been a barrier. Despite the faster block times, the total daily issuance of ZEC remains unchanged, preserving the coin’s 21 million supply cap and its four-year halving schedule.

The NU7 upgrade also introduces the Network Sustainability Mechanism. Under this new system, 60% of each block’s transaction fees are removed from circulation and stored in a reserve, while miners retain the remaining 40%. Additionally, a small, predictable portion of the reserve is reissued with each block’s reward. This mechanism is designed to ensure ongoing funding for network security, even as block rewards diminish over time due to halvings. The reserve is initially seeded with the historical funding shortfall from before the NU6 upgrade, providing a solid foundation.

NU7 also includes adjustments to shielded transaction limits, increasing Orchard throughput and reducing the potential sync load a spammer could impose on light wallets by about 37%. The testnet activation marks the first live run of these changes, and the Zcash Foundation is encouraging operators to upgrade and report any issues before a mainnet decision on October 20. If the testnet phase proceeds smoothly, the mainnet activation is targeted for November 5, following a coin-holder vote that supported faster blocks while maintaining the existing halving structure.