Vitalik Buterin says a new “quick confirmation rule” for Ethereum could give users a firm guarantee that a block won’t be canceled after a single slot, or about 12 seconds, a change that would significantly reduce one of the network’s biggest practical frictions for exchanges, bridges, and layer 2 systems.
The proposal, publicly described by Ethereum Foundation researcher Julian Ma and endorsed by Buterin on In Buterin’s words, the mechanism “allows you to get a firm guarantee that Ethereum will not come back after a slot (12 seconds). The security assumptions are (i) honest to qualified majority, (ii) network latency less than ~3s. So a step below the economic purpose, but very strong for many use cases.”
New Ethereum rule for faster confirmations
This distinction is important. Ethereum’s finality remains the strongest settlement guarantee on-chain, but it comes with a much longer wait time. Ma said the Fast Confirmation Rule, or FCR, reduced deposit times from the Ethereum mainnet to L2s and centralized exchanges to around 13 seconds, which he described as an “80-98% reduction for most L2s and exchanges.”
For users, the immediate consequence is speed. For infrastructure providers, the most important thing is efficiency. Ma argued that the mainnet’s slow confirmation forced exchanges, bridges, and rollups to operate under conditions of delay and uncertainty, particularly when processing deposits or synchronizing market activity across chains. “Transferring funds from Ethereum to L2s and centralized exchanges is slow. Users wait for minutes when using canonical bridges,” he wrote. “The new Fast Confirmation Rule (FCR) addresses this issue. It reduces the time to deposit Ethereum L1s to L2s or exchanges to around 13 seconds.”
He added that the rule should become “the new industry standard for L2s and exchanges,” and said it could begin rolling out in the coming months without a hard fork. It’s a remarkable design choice. Rather than introducing a consensus change that requires network-wide coordination, FCR can be activated as customers implement it, with nodes able to execute the rule automatically once support is operational.
Ma’s explanation presents FCR as a happy medium between today’s heuristics and the formal purpose of Ethereum. Most exchanges, L2s and solvers do not expect finality now. Instead, they rely on a block depth rule, or “k-deep,” essentially waiting until a transaction is buried under enough subsequent blocks. FCR takes a different route: it counts attestations rather than blocks. According to Ma, this makes it structurally faster while also giving it a provable security model that k-deep lacks.
The compromise is explicit. A quickly confirmed block is not finalized and the guarantee depends on stricter assumptions than the finality. FCR assumes a synchronous network, which in practice means that attestations arrive within about eight seconds, and it assumes that no adversary controls more than 25% of the ETH staked. Finality, on the other hand, is designed to last asynchronously and up to an adversarial threshold of 33%.
Nonetheless, Ma argued that the system gradually deteriorates when conditions deteriorate. “If the network is slow, FCR has a built-in fallback mode. Instead of quickly confirming a block in 13 seconds, it may take a little longer,” he wrote. “As soon as a sufficient number of certificates is issued, the blockage is quickly confirmed. In the worst case, the FCR becomes definitive again.”
This fallback solution is at the heart of the field. The mechanism does not claim that the risk of reorganization disappears; it claims to significantly reduce the waiting time while retaining deterministic guarantees when its assumptions are verified. Ma also stressed that if these assumptions hold true, a quickly confirmed blockade “will be finalized with certainty.”
At press time, ETH was trading at $2,319.
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