Jesse Pollak Says 200ms Blocks Live on Base Testnet, Mainnet Next

jessepollak, creator and lead of Base, said on Oct. 21, 2026 that 200-millisecond blocks are now live on the network's testnet, with a mainnet rollout to follow soon. An Oct. 19 post by dmericliu that Pollak quoted put the upgrade, named Denim, on Base Sepolia on Oct. 21 and on mainnet in November.

The figure marks a move to sub-second block production, a step change from the multi-second block times that have defined most Ethereum Layer-2 networks. Shorter block intervals reduce the gap between a transaction being submitted and being included, which matters most for applications where latency is visible to users — trading interfaces, payments, and onchain games.

Base is the Ethereum Layer-2 network incubated by Coinbase and built on Optimism's OP Stack. Pollak created the network and leads it.

What to watch

The announcement covers testnet performance only. Two questions remain open: the exact mainnet date within November, and whether 200ms blocks arrive there at the same cadence or in a staged rollout. Testnet results also do not by themselves establish how the network behaves under mainnet load, where activity and state growth are substantially higher.

For builders on Base, faster blocks change design assumptions around confirmation UX and transaction ordering. Teams typically wait for a mainnet commitment before reworking production systems around new block times.