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Zcash activates NU7, cutting target block time to 25 seconds

Zcash activated NU7 at block 3,543,405, cutting target block times to 25 seconds and reserving most transaction fees to help fund future mining rewards.

Crypto Daybook Newsroom2 min read

Zcash activates NU7, cutting target block time to 25 seconds

Zcash activated its NU7 network upgrade at block 3,543,405, cutting its target time between blocks from 75 seconds to 25 and making shielded payments—transactions that hide their details—faster to confirm. The CoinDesk report on NU7’s activation says the upgrade went live at 02:34 UTC on Nov. 6.

The shorter target interval does not mean every payment becomes usable in 25 seconds. Wallets, exchanges and merchants set their own confirmation rules. CoinDesk reported that the first 225 blocks after activation averaged about 39 seconds apart as mining difficulty adjusted toward the new pace.

How could NU7 speed up private payments?

Under NU7, blocks are meant to arrive three times as often. A block is a batch of transactions added to the Zcash network. More frequent blocks can shorten the wait for a first confirmation, though services that require several confirmations will still take longer.

The upgrade also puts limits on shielded activity in each block. Wallets scan the chain to find payments meant for them, and those limits reduce the amount of data a wallet may need to download. The Zcash Foundation’s Zebra 7.0.0 release notes say NU7 more than doubles Orchard’s capacity, from 2.9 to 6.6 transactions per second, while cutting worst-case sync bandwidth by about 37%.

What changes for miners and transaction fees?

Miners now receive 40% of transaction fees. The other 60% goes into a reserve for future block rewards. The Foundation says those reserved fees will begin to be reissued at mainnet block 8,939,664. NU7 keeps Zcash’s 21 million ZEC supply cap and its four-year halving schedule.

The upgrade also makes older version 4 transactions invalid. Zcash’s original Sprout privacy pool relies on that format, so any funds still there become unspendable under the new rules. CoinDesk reported that about 12,224 ZEC remained in Sprout at activation. A possible recovery method has been outlined, but no plan had been approved as of the report.

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