Zcash developers propose cutting block time from 25 to 20 seconds

What happened. On November 8 developers Dev Ojha, known as ValarDragon, and Evan Forbes posted a draft proposal on the Zcash community forum. They want to lower the target time between blocks from 25 to 20 seconds, put the question in the next community poll and consider it for the small NU7.1 upgrade.

Why so soon. NU7 went live on mainnet on November 5 at block 3,543,405. It cut block time from 75 to 25 seconds and added the NSM mechanism: 60% of fees from each block go to a reserve that later flows back into miner rewards. The authors of the new proposal say 25 seconds was never the final target.

What changes. A block every 20 seconds, with the 2 MB block size limit kept. Per block limits on private transactions shrink by a fifth, for example from 330 to 264, so the daily maximum stays the same. The block reward also shrinks by a fifth and the halving interval grows from 5,040,000 to 6,300,000 blocks. So daily ZEC issuance does not change.

Risks. The authors name the main risk themselves: more orphaned blocks, when two miners find a block at almost the same time. In their test with 80 miners in 12 regions, the orphan rate was 1.9% in one setup and 3.3% in a mixed one. For 25 seconds, 4.68% had been treated as acceptable. These are the authors' own numbers with no independent check yet.

Confirmed facts

• On November 8, 2026 developers Dev Ojha (ValarDragon) and Evan Forbes posted a draft ZIP on the Zcash forum to cut the target block time from 25 to 20 seconds.^[1][2]
• The authors want it in the next community poll and in the NU7.1 upgrade.^[1][2]
• NU7 activated on November 5 at block 3,543,405 and cut block time from 75 to 25 seconds.^[3]
• NU7 added the NSM mechanism: 60% of each block's fees go to a reserve and 40% to miners.^[3]
• Under the proposal the 2 MB block limit stays, and private transaction limits drop by a fifth, for example from 330 to 264 per block.^[1]
• Daily ZEC issuance is kept: the block reward drops by a fifth and the halving interval grows from 5,040,000 to 6,300,000 blocks.^[1]
• In the authors' test, the orphan rate at 20 seconds was 1.9% and 3.3% in two network setups.^[1]

Implications

• ConfirmedIf adopted, the first confirmation of a Zcash transfer gets faster on average, while daily capacity for private transactions does not grow.
• Our readingServices that count confirmations by block number rather than time may need to review their settings. This is our reading.
• Our readingTwo big changes in quick succession put more load on node and wallet teams, so the community may push back on the pace. This is our reading.

Still unknown

• When the community poll happens and how it ends
• The date of the NU7.1 upgrade
• Whether independent tests confirm the orphan rate numbers

Who it affects

Global. ZEC holders, miners, exchanges and anyone following privacy coins

Sources

1. Zcash Community Forum: Proposal: Lower Zcash block target spacing from 25s to 20s November 8, 2026 · official
2. Cointelegraph (via TradingView): Zcash devs propose another block time cut days after NU7 upgrade November 9, 2026 · media
3. Incrypted: Zcash Activated the NU7 Upgrade: Block Time Cut by Threefold November 6, 2026 · media