Solana is approaching a pivotal moment as it prepares for Alpenglow, a consensus overhaul that replaces both Tower BFT and Proof of History (PoH) to achieve sub-second finality. Delphi Digital notes that the upgrade introduces two protocol components, with Votor at the core replacing the Tower BFT’s incremental voting rounds with a lightweight vote aggregation model. Validators can aggregate votes off-chain before committing finality, allowing the block to be finalized in one or two confirmation rounds rather than multiple chained rounds. This could bring theoretical finality to about 100–150 milliseconds, roughly a 100-fold reduction from the current 12.8 seconds.
Votor would achieve this through two concurrent finalization paths: Fast Finalization triggers when a proposed block gains 80% or more of total stake approval in the first round and instantly finalizes. Slow Finalization would kick in when the first round reaches 60 to 80%, requiring a second round to exceed 60% before finality. Both paths run in parallel and aim to deliver finality even with partial network participation.
The other core is Rotor, redesigned to rework the SOL block propagation layer. Rotor will introduce stake-weighted relay paths that prioritize bandwidth-efficient propagation, making high-stakes validators with reliable bandwidth key relay points. In simulation, block propagation can occur as low as 18 milliseconds under typical bandwidth conditions. This upgrade is expected to roll out gradually, with initial activation anticipated in early to mid-2026.
The Kobeissi Letter reported that Solana’s on-chain spot volume reached $1.6 trillion in 2025, overtaking all off-chain exchanges except Binance. Jupiter Exchange data shows SOL on-chain volumes rising from 1% to about 12% of total volume since 2022, and 2025 saw SOL surpass Bybit, Coinbase Global, and Bitget in total trading volume, while Binance’s share declined from 80% to 55% since 2022, signaling a shift toward on-chain activity.
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