200ms Flashblocks are live on Base Sepolia

Base has launched Flashblocks on Base Sepolia testnet, a technology built by Flashbots that issues 200-millisecond "preconfirmation blocks" so transactions feel instant, with a full Base Mainnet rollout planned for this summer. Base currently creates a new block every 2 seconds, and Flashblocks are sub-blocks streamed to nodes every 200ms, each containing about 10% of a regular block's transactions by gas. Since enabling Flashblocks on Base Sepolia, Base reports up to a 10x reduction in transaction inclusion times. The announcement also notes that Flashblocks carry reorg risk and no revert protection in the initial release, and that the SLA for Flashblocks uptime is 99.9%, with fallback to two-second blocks during an outage.