Ethereum Hits Speed Bump After Fusaka Upgrade as Data-Heavy Blocks Surge

Ethereum’s Fusaka upgrade, activated on December 3, 2025, aimed to dramatically boost scalability by introducing Peer Data Availability Sampling (PeerDAS) and significantly increasing blob capacity—up to 8x initially, with subsequent Blob-Parameter-Only (BPO) forks pushing max blobs per block to 21 by early January 2026. These changes expanded data throughput for Layer-2 (L2) rollups like Arbitrum, Optimism, and Base, lowering fees and driving record activity, including nearly 2.8 million daily transactions and a surge in active addresses.

However, recent research from MigaLabs (published January 27, 2026) reveals emerging performance issues: the network struggles to reliably process data-heavy blocks, particularly those with 16+ blobs. Missed-slot rates rise sharply in these cases, indicating higher demands on validators for propagation, storage, and bandwidth. This stems from the rapid increase in blob usage as L2 networks post more compressed transaction data to Ethereum’s base layer for settlement and verification.

While the network operates normally overall—no widespread congestion or failures reported—the heavier blocks raise decentralization concerns. Smaller node operators face elevated hardware requirements, potentially discouraging individual participation and concentrating control among well-resourced providers. Developers anticipated such transitional pressures with higher data loads, viewing them as a sign of growing L2 adoption rather than a core flaw.

Core teams are actively monitoring via metrics and discussions, with potential optimizations including enhanced data pruning, improved compression, better propagation protocols, and future upgrades (e.g., Glamsterdam in H1 2026) to further ease node burdens. JPMorgan analysts note the post-Fusaka activity spike but question long-term sustainability amid L2 competition and rival chains.

The situation highlights Ethereum’s scaling trade-offs: prioritizing massive throughput for L2s while preserving security and decentralization. Ethereum remains stable, with low fees and high usage reflecting success in its rollup-centric roadmap. Analysts see current strains as evolutionary growing pains, not a setback, as the community iterates toward full Danksharding-like capabilities.