Ethereum developers propose FCR to speed up L2 and exchange confirmations

Ethereum client teams are testing an opt-in mechanism that could cut the time some layer-2 networks and exchanges wait to recognize mainnet deposits, allowing them to process transactions much faster.

Dubbed the Fast Confirmation Rule (FCR), the proposal is expected to bring confirmation times down to around 13 seconds, according to Ethereum researcher Julian Ma.

By using this approach, platforms can move away from systems that rely on canonical bridges, where transfers typically take up to 13 minutes to reach full confirmation. However, many already rely on “k-deep” confirmation rules, which offer no formal guarantees. A transaction in such models is only treated as confirmed once a predefined number of blocks have been added on top of it.

Developers say the rule can be introduced without hard-forking, though client and API integration is still required.

Client teams are already working on implementations, with deployment expected to allow nodes to adopt the rule without network-wide coordination.

When using FCR, rather than counting blocks, the system evaluates validator attestations to determine whether a block is safe to treat as confirmed. This can solve the issue of slow bridging between Ethereum L1 and downstream platforms.

It does this by relying on two assumptions: that validator messages propagate quickly across the network and that no single entity controls more than 25% of staked Ether. While these thresholds fall short of Ethereum’s stricter finality guarantees, they are considered sufficient for most real-world use cases.

In cases where more security is needed, the system waits longer before confirming a block, Ma explained, adding that “it’s a feature, not a bug.”

Mixed community reaction

Ethereum co-founder Vitalik Buterin said the mechanism can provide a “hard guarantee” that a transaction will not be reverted after a single slot under the right network conditions.

But other community members remained skeptical about the proposal. Some argued that the model leans heavily on trust assumptions and may face challenges under stressed network conditions.