Optimism Targets 200 ms Subblocks with Potential Compatibility Risks
Optimism is pushing network speeds to 200 ms through subblocks on its OP Mainnet, cutting the preconfirmation interval from 250 milliseconds in a rolling change targeted for Aug. 31.
The 20% speedup carries a quiet compatibility risk as four fields will remain in each streamed payload but stop carrying usable data: state_root, block_hash and withdrawals_root will be all-zero values, while withdrawals will be an empty list.
Most applications are on the safer side of this boundary, connecting to a subblocks-aware RPC provider and using standard Ethereum methods, often with the pending tag. However, some apps ingest the WebSocket stream themselves and rely on raw fields from providers, which need to prevent placeholder roots and block hashes from entering downstream state.