Solana's Alpenglow upgrade launching next week will reduce finality from 12.8 seconds to ~150 milliseconds.
Tech & Launches ·
Solana is scheduled to activate its Alpenglow upgrade on October 21, retiring its original consensus mechanism and dramatically reducing transaction finality. The upgrade will compress finality from approximately 12.8 seconds to around 150 milliseconds—a roughly 85-fold improvement. Anza, the development team leading the work, characterized the transition as 18 months of engineering compressed into a single slot deployment.
Finality marks the point at which a transaction becomes irreversible and payment cannot be reversed. Under the new system, Solana gains resilience against simultaneous malicious behavior from 20 percent of staked SOL plus an additional 20 percent going offline, compared to the previous threshold of roughly one-third of stake. This shift addresses concerns around network stability that have historically affected Solana's reputation.
A notable side effect will emerge immediately after activation: recorded transaction throughput figures are expected to decline substantially. The current metrics count validator votes as on-chain transactions, but Alpenglow routes voting directly between validators instead. No change occurs in actual user volume or application activity; the decline reflects a measurement artifact. The upgrade also represents only phase one of a two-part process, with phase two lacking a target date. Solana previously postponed an Alpenglow activation scheduled for September 28.