Offchain Labs Pushes Back on Vitalik as Debate Over Ethereum’s Future Execution Model Intensifies

A new technical rift has emerged within the Ethereum research community as Offchain Labs, the core developer behind Arbitrum, publicly challenges Vitalik Buterin’s enthusiasm for adopting the RISC-V instruction set architecture as the foundation for Ethereum’s next-generation execution layer. In a detailed analysis posted on Ethereum Research, four of the company’s researchers argue that WebAssembly, or WASM, remains a more robust and future-proof choice for Ethereum’s Layer 1 smart contract format.

The debate stems from Buterin’s proposal earlier this year to replace Ethereum’s long-standing EVM bytecode with the open-source RISC-V instruction set architecture. His position is grounded in the rapid progress of zero-knowledge proving systems, many of which operate most efficiently on RISC-V. Buterin suggested that such a transition could sharply reduce the cost of ZK proofs, in some cases by up to a hundredfold, and create a cleaner path for integrating ZK-based scalability across the network.

In their response, Offchain Labs researchers Mario Alvarez, Matteo Campanelli, Tsahi Zidenberg and Daniel Lumi emphasize that the objectives of reducing proving costs and designing the right long-term execution format are not always aligned. They argue that Ethereum should separate the instruction set used to deliver and store smart contracts from the instruction set used by ZK virtual machines to generate proofs. According to their analysis, this distinction would preserve flexibility as proving technologies evolve while maintaining an execution layer optimized for readability, safety and long-term maintainability.

The team cites its own progress as evidence. Arbitrum’s upcoming architecture allows WASM-based Stylus smart contracts to be ZK-proven using a RISC-V backend. By compiling WASM into RISC-V for proving purposes, they demonstrate that Ethereum does not need to enshrine a single instruction set to serve both smart contract delivery and proof generation. In their view, binding Ethereum’s L1 to RISC-V too early risks locking the protocol into a proving paradigm that could quickly become outdated.

They note that recent shifts from 32-bit to 64-bit RISC-V ZK engines hint at a rapidly evolving landscape where future breakthroughs may arise outside traditional hardware-oriented ISAs. At the same time, WASM-native ZK-VMs such as Ligero’s Ligetron show that proof efficiency may not remain exclusive to RISC-V for long. Meanwhile, real-world proving costs have already fallen dramatically, averaging about two and a half cents per Ethereum block and trending downward, making extreme optimization less urgent than before.

The researchers also highlight structural advantages of WASM. They point to its modularity, mature validation rules and extensive tooling ecosystem, which allow developers to update and optimize code safely without risking compatibility failures. WASM executes natively on common hardware, while most Ethereum nodes would have to emulate RISC-V, introducing overhead. The team describes WASM as a universal layer capable of bridging diverse programming languages and execution backends, much like the role of the Internet Protocol in networking.

Their critique does not dismiss the importance of RISC-V but questions whether it should define Ethereum’s long-term execution model. Instead, they call for a layered architecture where Ethereum maintains an adaptable delivery format while allowing ZK-VMs to innovate independently.

The exchange marks an important moment for Ethereum as it approaches a new phase of technical maturation. Whether the network leans toward RISC-V, WASM or a hybrid approach will shape how contracts are built, proven and executed for years to come. For now, the discussion highlights a growing consensus that Ethereum’s future may rely more on modular design than on betting everything on a single instruction set.