Anza, a core developer of Solana, announced on October 21 that the new Alpenglow consensus protocol is live on mainnet. Its goal is to reduce the delay between a block being proposed and becoming final to about 150 milliseconds, or 0.15 seconds.
Confirmation that a transaction has been processed in a block is different from finality, when the network can no longer reverse it. Under the previous system, validator votes were recorded in blocks like transactions, and finality was established by checking votes accumulated across several subsequent blocks. Alpenglow is designed to reduce the wait for finality by having validators exchange votes directly and produce proof that sufficient agreement has been reached. Anza said the consensus mechanism was changed on the live network while preserving the existing transaction ledger.
The Solana Foundation said the roughly 150-millisecond figure is an expectation based on the stake distribution used in testing, not a guarantee. Actual finality times will depend on validators' stake distribution, network latency and whether voting concludes in one round or requires two. The public materials did not provide a distribution of finality times measured on the production network after the transition.
The way ordinary users sign and submit transactions has not changed. The transition changes the procedure for agreeing on transaction order and finality, not the way transactions are executed.