Breaking Down Zcash's Scaling Roadmap: How 5 Key Technological Upgrades Position It as a High-Throughput Privacy Currency?

Author: William M. Peaster (Senior Analyst at Bankless)

Edited by: TechFlow

TechFlow Reads: In the long evolution of the public blockchain sector, scalability has always been the elusive technical holy grail for all privacy blockchains. With the explosive iteration of on-chain analysis tools and AI tracking technologies, user funds and transaction privacy under fully transparent ledgers have been nearly eroded away. However, native zero-knowledge privacy computing has long been trapped in throughput bottlenecks due to the heavy burden of full-node verification and state bloat.

On the eve of this week's milestone NU7 network upgrade (November 5-6), Zcash co-founder Sean Bowe and core protocol contributor Dev Ojha have unveiled a comprehensive two-year systematic scaling roadmap. They plan not only to drastically reduce block times from 75 seconds to 25 seconds, but also to leverage homomorphic encryption-based PIR private retrieval enabled by cheapened AI compute, Tachyon recursive proof aggregation, and stateless node compression to target high concurrency of 50,000 TPS. TechFlow provides an in-depth full-text translation here, guiding you through the next wave of hardcore technological breakthroughs for privacy public chains.

From the shorter block times officially launching this week to the private RPC payment system still in early conceptual stages, here is the complete roadmap systematically revealed by the Zcash developer team in the latest episode of the Bankless podcast.

Scalability has always been the dream holy grail of privacy public chains. Fortunately, for the Zcash community, its core developers have already formulated a systematic plan to expand the scale of private ZEC payments. Even more excitingly, the first step toward this goal—a major upgrade—is officially landing this week.

In the latest episode of the Bankless podcast, titled "The Complete Zcash Roadmap," Zcash co-founder Sean Bowe and protocol core contributor Dev Ojha engaged in an in-depth discussion with host David Hoffman. They detailed how to gradually push Zcash's current throughput of approximately 60 KB/s toward Ojha's long-term goal: 50,000 transactions per second (equivalent to 100 MB/s throughput, achieving an astonishing scaling leap of up to 166,500%).

This article will quickly guide you through the core framework of this vision and outline the five foundational upgrades supporting this roadmap.

Figure: Schematic of Zcash's long-term network performance and throughput scaling ladder

Faster Block Times

As I pointed out when the NU7 timeline was finalized in September, Zcash's ninth major network upgrade will drastically compress block times from 75 seconds down to 25 seconds. The activation block height for NU7 is expected to be officially reached during the night of November 5th to 6th UTC.

According to Ojha, assuming block size remains constant, this shift will directly increase the chain's bandwidth by approximately 3x, reaching about 180 KB/s. Building on this, he noted that mature technologies already used by other blockchains can be leveraged, such as erasure coding (splitting blocks into redundant data chunks so nodes can reconstruct blocks without downloading all data) and more efficient Gossip communication mechanisms between nodes.

Notably, while pushing forward with all of this, Zcash remains committed to the Proof of Work (PoW) mechanism. Ojha praised this effort as "the first time ever building a high-throughput Proof of Work network."

However, there is an objective characteristic that will need to be considered: mining possesses inherent randomness. Therefore, at an average 25-second block interval, approximately 1% of blocks will be generated extremely fast within about 250 milliseconds, while another 1% of blocks will take longer than 110 seconds to generate.

Upgrade Status: Faster block speeds are scheduled to officially go live this week with the NU7 upgrade. The more challenging task of cracking through throughput limitations has been defined by Ojha as a core mission "over the next two years."

PIR Private Retrieval Wallets

As Ojha stated: "The really tricky problem lies in how do you know you received money?"

Under Zcash's shielded address system, no external observer can learn who sent funds to whom. This also means your wallet cannot query its own account balance directly from the server like an Ethereum wallet does.

Historically, Zcash wallets have had to download every single transaction on-chain and compare them locally to figure out which ones belong to them. Once blockchain throughput reaches 100 MB/s, this primitive model requiring every terminal to download full transaction volumes will inevitably completely collapse.

This is where Private Information Retrieval (PIR) shines. Under this new paradigm, your client wallet sends an encrypted query request to the server storing on-chain data; leveraging homomorphic encryption (which allows mathematical operations to be performed directly on ciphertext), the server can precisely return the query results without knowing exactly what was queried.

Interestingly, the current booming AI wave is precisely the key catalyst that makes this privacy technology practical. Ojha explained that this specific type of PIR ultimately boils down to massive matrix-vector multiplication operations, which happens to be exactly the mathematical domain where GPUs have become incredibly cheap and fast due to the AI compute arms race.

To give fair credit, host David also raised reasonable skepticism in the conversation: querying a server sounds like introducing a trusted third-party intermediary. In response, Ojha clarified that PIR's operational mechanism will function exactly like RPC nodes in the Ethereum ecosystem; anyone can freely build their own service nodes, and wallet clients can seamlessly switch freely among numerous different providers.

Upgrade Status: Already deployed in practice. Bowe revealed that Zcash has already adopted PIR technology in a recent holder on-chain governance vote, which he believes sets a historic precedent in the crypto industry.

Tachyon Proof Aggregation

Tachyon is a cryptographic infrastructure refactoring project personally led by Bowe, specifically aimed at tackling the system's two core bottlenecks. The foremost bottleneck is proof computation, because under the current architecture, full nodes must individually verify the zero-knowledge proofs for every shielded transaction one by one.

To overcome this obstacle, Tachyon is developing Recursive Zero-Knowledge Proofs (Recursive SNARKs, i.e., using one proof to verify others), thereby bundling and aggregating massive numbers of proofs. This technology will significantly flatten the verification burden for full nodes, allowing them to simply verify one aggregated ZKP at any given point rather than sequentially verifying thousands of independent proofs.

Worth highlighting is that once this system is deployed online, it will immediately yield at least a 5x scaling performance boost. If this logic sounds familiar, it's because it indeed has precedents. David likened Tachyon's proof aggregation work to the ZK Rollup transaction batching mechanism on Ethereum, to which Ojha frankly acknowledged Ethereum's pioneering contribution in being the first to deploy recursive proofs in a production environment.

Upgrade Status: Actively in development. Tachyon's code is currently being integrated into the underlying cryptographic protocol stack behind Zakura full nodes, but it has not yet been activated on the mainnet, and official public release timelines have not been announced.

Stateless Blockchains

The second focus of the Tachyon project tackles the state bloat problem. Every time a user spends shielded ZEC, the network records a nullifier (the unique tag preventing double-spending of the same funds). Unlike transparent ledgers that can periodically prune historical data, privacy blockchains must permanently preserve this continuously growing nullifier list.

Tachyon is also dedicated to compressing this massive state to its absolute limit. According to Ojha, full nodes will only need to retain active real-time state for roughly the most recent month, while older historical data will transition into structures that users can trustlessly retrieve when needed. Bowe credited this innovative technology to a research paper jointly published by him and cryptographer Ian Miers.

It must be clear that Ojha frankly pointed out, "you absolutely cannot cram 50,000 extreme TPS into a Raspberry Pi," but at this level of extreme compression, running a full node will only require a few hundred gigabytes of storage, and will certainly never evolve into a storage disaster of tens or hundreds of petabytes.

Upgrade Status: Currently, as a core module of the Tachyon project, it is in active development.

Private RPC Subscription Model

The final upgrade involves economic mechanism design more than anything else, and is also the one currently in the earliest conceptual stage among the aforementioned technical roadmaps.

In the Ethereum or Solana ecosystems, wallet developers like MetaMask and Phantom fund the operation of RPC servers (the underlying infrastructure responsible for feeding on-chain data to user wallets), partly because they can monetize via user traffic. However, Zcash never tracks its users, so it currently relies solely on a very small number of volunteer providers offering this data support for free.

To prevent the system from becoming unsustainable due to long-term "reliance on altruism," Ojha conceived a private subscription payment model. Users can pay upfront to purchase query quotas, such as 1,000 queries per month; the wallet converts this quota into a credential token, and each subsequent query consumes one token, utilizing the exact same cryptographic mechanism Zcash uses to prevent payment double-spending.

Therefore, under this paradigm, RPC service providers can accurately verify whether a user holds a valid subscription credential, while remaining completely unaware of exactly which specific subscriber is initiating the query.

Upgrade Status: Still at the conceptual design stage, though Ojha emphasized that this is a clearly solvable engineering problem.

The Road Ahead

As for why all of this feels particularly urgent and important at this juncture, Bowe's core argument is that the explosive proliferation of AI tools has lowered the barrier for tracking and pinpointing specific individuals across transparent public ledger accounts to an extremely low, near-zero cost.

Beyond the aforementioned exciting technical blueprint, this roadmap podcast episode also deeply explored Zcash's long-term post-quantum computing plans, formal verification, and on-chain governance architecture. The governance segment perfectly complements and echoes my recent in-depth analysis regarding the debate over the existence or abolition of the Zcash Developer Fund.