Ethereum Fusaka upgrade activates, paves way for higher throughput and lower Layer 2 costs

Ethereum moved forward with a major protocol upgrade as Fusaka activated on mainnet on Dec. 3, 2025 at roughly 21:49 UTC, according to core developers and multiple crypto outlets. The hard fork bundles about a dozen Ethereum Improvement Proposals focused on data availability, node efficiency and network throughput, a set of changes stakeholders say will reshape how rollups and validators interact with on chain data markets.

Among the most consequential items in Fusaka is Peer Data Availability Sampling, referenced as PeerDAS and tracked as EIP 7594, which changes how validators verify blob data. Instead of requiring full downloads of large data objects, the network will rely on sampled verification, a move designed to reduce bandwidth requirements for node operators and make validator operation more efficient.

Fusaka also introduces cryptographic precompiles for secp256r1 signatures, enabling native support for passkey style credentials that underpin modern web authentication. Native precompiles make verification of these signature types cheaper in gas and faster to execute than through software libraries, smoothing integration of web authentication paradigms with Ethereum accounts.

The upgrade changes default gas capacity rules as well, with reported configuration adjustments moving current defaults from 30 million gas toward higher levels such as 60 million gas. Those adjustments are intended to unlock higher throughput for on chain transactions and rollup calldata at the block level, while the protocol includes new safeguards on heavy opcodes to limit attack surface for denial of service vectors.

Fusaka is the first step in a phased rollout. Mainnet activation is to be followed by two Blob Parameter Only forks, or BPO forks, which expand blob capacity for data availability. The first BPO is expected roughly a week after Fusaka, and a second BPO is slated for January. Together these parameter updates are projected to double or more blob throughput available to rollups, which in turn should lower Layer 2 data costs for users and developers who rely on blobs to post aggregated transaction data.

A key target of the suite is to rewire blob fee economics so data availability markets remain functional as throughput scales. By making verification cheaper and increasing raw blob capacity, the protocol designers aim to keep fees predictable and to prevent market distortions that could arise as more applications push large volumes of calldata.

CryptoSlate and other outlets published explainer coverage on Dec. 2 ahead of the scheduled activation, preparing users and developers for the changes. The upgrade represents one of the more substantive adjustments to the data availability layer since the adoption of blobs, and its phased structure signals an emphasis on incremental capacity increases rather than a single disruptive change.

If the planned BPO forks proceed as scheduled, rollups and consumers of on chain data can expect meaningful reductions in costs in the coming months, while validators will rely more heavily on sampled verification to manage bandwidth and storage demands. The net effect will be a test of whether protocol level efficiency improvements can keep pace with growing rollup demand while maintaining network security and decentralization.