Gemini, the crypto exchange controlled by the Winklevoss twins, has replaced the software running its Zcash nodes, cutting the time its systems need to catch up with the network from nearly a full day to just over six hours. The switch, announced Tuesday, is preparation for Zcash’s planned NU7 upgrade, which would cut block times from 75 seconds to 25 seconds and triple the workload for every computer following the chain.
Gemini moved from Zebra, the long-standing reference client, to Zakura, an open-source Zcash full node written in Rust that is a consensus-compatible fork of Zebra. In the exchange’s deployments, Zakura reached the chain tip in a little over six hours after starting or falling behind. Zebra took close to a day for the same task. Zakura’s developers published their own benchmark showing four hours and 20 minutes against nearly 21 hours for Zebra.
Why the upgrade forces a software change
NU7, the next Zcash network upgrade, would shorten the interval between blocks from 75 seconds to 25 seconds. Nodes would have to receive and validate roughly three times as many blocks in the same period. That raises the bar for sync speed, storage efficiency and recovery time, which is exactly where Zakura’s design is aimed. The fork was built so operators can sync, prune and recover at the scale Zcash is heading toward, in the words of Gemini’s own announcement.
Developers are targeting Nov. 5 for mainnet activation, with the upgrade reaching the test network on Oct. 6 and a final go or no-go decision scheduled for Oct. 20 after the testnet results are reviewed. Gemini has not published performance tests showing how its Zakura deployment behaves under the faster 25-second schedule, so the exchange’s readiness claim rests on the sync benchmarks rather than a live rehearsal of NU7 conditions.
Zakura also supports pruned snapshots for node recovery. Gemini described the snapshots as about 12 gigabytes and roughly 680 times faster for bootstrapping a new node than standard peer-to-peer synchronization, where the machine downloads the entire transaction history from scratch. For an exchange running redundant infrastructure across regions, that gap is the difference between a brief maintenance window and a multi-day rebuild.
“Deposits and withdrawals will work exactly as before.” – Gemini, on the software switch
Zcash’s moment
The infrastructure work lands during a stretch of unusual attention for Zcash. The privacy-focused token ran to $1,683 earlier this month before cooling about 12% as funding rates turned negative and leveraged longs unwound, per CoinDesk. It is still up roughly 14% on the week. Coinholders voted on Sept. 14 to adopt the faster block schedule in NU7, and developers have begun folding Project Tachyon, the codebase for faster private payments, into Zakura Common as they work toward a long-term target of more than 50,000 private payments per second.
The hacker behind the $387.5 million Bitget theft has also put Zcash in the news for less welcome reasons, moving about $4 million of stolen ZEC into the network’s private pool, where payments hide their senders, recipients and amounts, making the funds harder to trace. Three transfers pushed roughly 15% of the stolen ZEC into the shielded pool. Privacy coins draw regulatory scrutiny when stolen funds disappear into shielded pools, and every exchange listing decision now weighs that risk.
The price run has its skeptics. ZEC’s rally this year has been driven partly by retail enthusiasm for privacy narratives and partly by leveraged positioning, and negative funding rates in the last week suggest the speculative side was crowded. A network upgrade that actually ships, on schedule, would be a fundamental rather than narrative driver, which is why the October test window matters beyond engineering circles.
What it means for users and operators
For Gemini customers, nothing changes at the interface level. The exchange said Zcash deposits and withdrawals work exactly as before. The change matters for the plumbing behind them: faster sync means less downtime after outages, and the snapshot system means a replacement node can be standing in hours rather than days if something breaks.
For other node operators, exchanges, indexers and block explorers, NU7 will be a real test. Tripling block frequency raises storage and bandwidth costs for anyone verifying the chain, and operators who run slow software will fall behind and serve stale data. Gemini’s early move signals to the rest of the ecosystem that the reference client may no longer be adequate for production use at the new block rate.
The Winklevoss twins have a second reason to care about Zcash performance. Through Cypherpunk Technologies, a company they control, they hold exposure to Zcash mining, so a faster and healthier network supports that position as well as the exchange’s custody business. The twins have been public about their interest in privacy technology this year, and Gemini’s Zcash listing and infrastructure spend are consistent with that posture.
The timeline ahead
The sequence from here is fixed. Testnet activation on Oct. 6, a mainnet decision on Oct. 20, and, if the numbers hold, mainnet activation on Nov. 5. If the testnet shows nodes struggling under the 25-second schedule, developers can delay, as Ethereum did repeatedly with its own upgrades before landing Glamsterdam, which is itself scheduled for Sepolia testing on Oct. 6.
Gemini’s switch is the first concrete infrastructure commitment tied to NU7 from a major exchange. Whether others follow before the October test window will show how much of the industry is actually prepared for Zcash to run three times faster. Exchanges that wait for the mainnet decision will have less margin for error, since node migration, testing and failover drills take weeks, not days.