Vitalik Praises Lean Ethereum Team Progress on Long-Term Scaling Roadmap

“The Lean Ethereum team has been doing a truly amazing job kicking into gear this year, and delivering on all fronts to ensure Ethereum’s long-term scaling, decentralization, and resilience,” said Vitalik on Sunday.

He added that he expects all of these ideas to be ready to kick into gear at roughly the same time as the short-term scaling roadmap delivers on its key milestones.

Lean Ethereum is a minimal zkVM (zero-knowledge virtual machine) proposal from developers intended to provide a recursion-friendly virtual machine for ZK-proofs. Essentially, it is a stripped-down, more efficient version of Ethereum’s computing engine.

Ethereum Scaling Roadmap

Vitalik explains that LeanVM is designed to integrate safely with mainnet operations.

“The point is that the Lean roadmap lags behind the short-term scaling milestones so that ideally the former is ready to go exactly once the latter is all on mainnet,” he said.

The lean Ethereum team has been doing a truly amazing job kicking into gear this year, and delivering on all fronts to ensure Ethereum’s long-term scaling, decentralization and resilience.

I expect all of these ideas will be ready to kick into gear at roughly the same time as… https://t.co/4uimhAZI5N

— vitalik.eth (@VitalikButerin) September 6, 2025

Developers are intentionally making the “lean” improvements lag behind the immediate scaling solutions, so everything is ready to work together seamlessly.

According to the Lean Roadmap, the specifications are still being ironed out, building will start in 2026, and testing will start in 2027. The long-term vision is to complete the roadmap in 4-5 years so Ethereum can go into “maintenance mode.”

LeanVM is expected to reduce costs for large-scale computations, speed up recursion for ZK-proof computations, and maintain network decentralization and security.

The next major upgrade for the Ethereum mainnet is “Fusaka,” which is slated for November. The upgrade focuses on making Ethereum more efficient for layer-2 rollups while improving the base layer’s performance and accessibility.

Protocols Are Works of Art

Vitalik also talks about protocols being “works of art” with minimal code, emphasizing that blockchains should be elegant and simple, not messy patches that accumulate over time.

“Protocols are not a dirty get-it-out-there thing that you vibe-code, where you accept permanent accumulating garbage in the name of short-term convenience. Protocols are a work of art. They should look as such.”

Ethereum has been criticized for its lack of scaling and slow development compared to rival blockchains. However, proponents claim it is better to be slow and thorough with 100% uptime than to rush out a faster blockchain that is plagued with reliability issues.