Ethereum advances Glamsterdam upgrade with successful performance tests

Ethereum is progressing with its Glamsterdam upgrade, which aims to increase network capacity and reduce transaction fees. Recent tests successfully implemented new block-building rules, and the Nethermind execution client completed over 2,300 performance tests, processing approximately 570.7 billion gas in a three-minute window.

Key technical features of the upgrade include ‘Block-level Access Lists’ to enable transaction parallelization and ‘Enshrined Proposer-Builder Separation’ (ePBS) to integrate block building into the protocol. Developers also tested increasing the block gas limit from 60 million to 200 million to accommodate higher throughput.

The next major milestone is the Sepolia testnet fork scheduled for October 6. However, developers have warned of potential ‘fake builder’ attacks on the Sepolia network. Because testnet ETH has no economic value, attackers could use multiple identities to win block auctions and then refuse to release transaction data, potentially disrupting the testing process. While these risks do not affect the Ethereum mainnet, they could complicate the evaluation of the upgrade's stability. The official roadmap targets a mainnet implementation in the fourth quarter of 2026.