Zcash’s landmark NU7 upgrade goes live, speeding up private payments
Zcash activated its NU7 upgrade Friday, cutting block times from 75 to 25 seconds and speeding up private payment confirmations.
The upgrade went live at block 3,543,405, mined at 02:34 UTC. By 04:59 UTC, the network had produced another 225 blocks, averaging about 39 seconds apart. Mining difficulty was still adjusting toward the faster pace.
Faster confirmations could make private payments easier to use at shops, through exchanges or when moving funds between blockchains. A merchant could see a payment's first confirmation in about 25 seconds on average.
Technical adjustments
Zakura, Zcash node software built by Valar Group and Project Tachyon, tested 25-second blocks on 80 computers across 11 regions. Under demanding conditions, 3.43% of mined blocks were discarded, compared with 1.57% at the old pace.
The software checks a transaction when it first arrives, then remembers parts of that check so it does not have to start from scratch when the transaction appears in a block.
Transaction limits
NU7 limits private transaction activity per block to reduce wallet downloads. The worst-case daily download burden drops from 271 megabytes to 169, while capacity for simple private payments could more than double from about three to over six per second.
Fee changes
Miners now receive 40% of transaction fees, with 60% removed from circulation and recorded in a reserve that will start feeding future block rewards around February 2031, preserving Zcash's 21 million coin supply cap.
The upgrade also retired Zcash's original Sprout privacy pool from 2016, leaving about 12,224 ZEC unspendable. Co-founder Sean Bowe has outlined a possible recovery mechanism, though none has been approved.
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