Zcash developers propose cutting block time to 20 seconds

Developers Dev Ojha, known as ValarDragon, and Evan Forbes want the change considered for the future NU7.1 upgrade. NU7 went live on Nov. 6 at block 3,543,405, cutting the target interval from 75 seconds to 25. Under the new proposal, one confirmation would take about 20 seconds on average; a service requiring three would wait about 60 seconds, down from 75. Actual times vary, and exchanges and other providers set their own confirmation rules. Retail payments, exchange deposits and cross-chain swaps are among the uses developers say could benefit.

Faster blocks can increase the risk of orphaned blocks, which are discarded when miners produce competing blocks. ZecBlock’s tracker recorded an orphan rate of 0.69% in the 24 hours ending early Monday, compared with about 0.66% before NU7. Across the full period since the upgrade, the rate was 1.29%, following an initial increase. Ojha said the recent rate was better than he had anticipated. The tracker expanded from one node to ten shortly before NU7, making earlier and current readings not directly comparable.

In tests with 80 miners across 12 regions, the proposed interval produced orphan rates of 1.9% to 3.3%, depending on mining software. Earlier tests of 25-second blocks recorded 4.68%. The draft would lower the maximum shielded actions per block from 330 to 264 while leaving the 2 MB block-size limit unchanged, preserving daily shielded transaction capacity. It would also adjust the block subsidy and halving interval to maintain the existing issuance schedule and 21 million ZEC maximum supply.

The plan would extend the difficulty-adjustment averaging window from 102 blocks under NU7 to 128. Ojha estimated this could narrow difficulty fluctuations from roughly -40% to +30% to -20% to +15%; actual performance remains to be seen. The proposal would keep the recommended three-block confirmation anchor, whose expected duration would fall from 75 to 60 seconds, and raise default transaction expiry from 120 to 150 blocks to preserve its expected duration. Ojha and Forbes want the change put to a community poll. No vote outcome or activation schedule has been announced.