Sui consensus skips the certification round that older designs required

How Mysticeti Rewrote the Rules

Most legacy blockchain consensus designs require each proposed block to collect signatures from a quorum of validators before it is considered valid. That certification round adds meaningful overhead: under the older Narwhal-Bullshark setup that @SuiNetwork previously ran, a commit could take as many as three round trips before it was finalised.

Mysticeti removes that bottleneck. According to the Sui Foundation, the protocol takes a different approach: validators simply sign and share their blocks directly, without waiting for a formal certification step. A novel commit rule then decides when each block is ready, meaning every block can be committed as soon as the rule is satisfied, with no added delay. The result is a consensus commit time of roughly half a second, with single-owner transactions settling even faster at around 250 milliseconds.

The academic paper behind Mysticeti, published on arXiv, confirms the headline numbers: Mysticeti-C is described as the first Byzantine consensus protocol to achieve wide-area network latency of 0.5 seconds for consensus commit while simultaneously maintaining throughput exceeding 200,000 transactions per second. Integrating it into Sui produced over four times latency reduction compared to what came before.

Parallel Proposals and the Mysticeti v2 Extension

Sui uses a directed acyclic graph-based consensus protocol called Mysticeti that optimises for both low latency and high throughput. Mysticeti supports multiple validators proposing blocks in parallel, which uses the full bandwidth of the network and provides censorship resistance. That is a deliberate departure from older designs, where validators effectively took turns, and each slot was limited to a single block per validator.

Dropping the certification round creates a side effect: without the one-block-per-validator-per-slot constraint that the old signing round enforced, a validator can now propose more than one block. The commit rules carry the responsibility for handling that. @SuiNetwork addressed this further with Mysticeti v2, which builds on top of the original rather than replacing it. Validators now cast explicit votes only for rejections, with accept votes expressed implicitly through ancestor block links, and transaction certifications evaluated only when necessary. Mysticeti v2 also folds a fast path into the DAG structure itself, allowing eligible transactions to settle at even lower latency.

Compared with Bullshark on Sui Mainnet, the upgrade delivered an 80% latency reduction, bringing average consensus time from roughly 1.9 seconds down to around 400 milliseconds. That improvement, combined with a reported 40% reduction in CPU usage for consensus in production, makes the architecture a meaningful step forward for validators and application developers building on the network.

Sources:
Sui Foundation: Mysticeti Set to Supercharge Consensus on Sui
arXiv: Mysticeti: Reaching the Limits of Latency with Uncertified DAGs
Sui Foundation: Mysticeti v2: Faster and Lighter Sui Transaction Processing