Donovan Choy

This is a segment from the Lightspeed newsletter. To read full editions, <a href="https://blockworks.co/newsletter/lightspeed" target="_blank" rel="noreferrer noopener">subscribe</a>.



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Solana validators have begun voting on SIMD-0326, the governance proposal for its new <a href="https://blockworks.co/news/solana-alpenglow-next-gen-consensus-layer-speed">Alpenglow consensus protocol</a>.



The proposal needs at least 33% of validators to reach quorum. As of this morning, at least 11.8% (135) of Solana’s ~1.3K validators have voted in favor, based on <a href="https://dune.com/kagren0/simd-0326-voting-status">Dune</a>.



<figure class="wp-block-image"><img decoding="async" src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXe8qXRrteOvrnBbGBNTTt81f6yKynyWZAN1kemQ1T-A85QMfoXg0kKkFi75J-4J3xZq_e3qRx35Cy0ARfrnQdTBFeUvvdQbvN0AnQI_dwgW4XwJQ18BH1zZ1QBK2OArDrejNrui?key=g93vGr6mMwKrQnYKnL2EnQ" alt=""/></figure>



When you send a transaction on Solana today, the chain takes about ~12.8 seconds (32 slots * 0.4s slot time) to reach deterministic finality, though it is also sometimes informally referred to as having a soft/optimistic transaction finality of 500-600ms.&nbsp;&nbsp;



12.8 seconds is fast compared to the 12.8 minute finality of Ethereum’s Gasper consensus, but it pales in comparison to the consensus speed of newer chains like Sui’s Mysticeti, with 390-500ms.



Alpenglow <a href="https://blockworks.co/news/solana-prepares-for-alpenglow">promises to collapse</a> the 12.8-second time window further to 100-150ms, bringing about a 100x improvement, depending on where a validator is geographically located.



It does so by eliminating a few core legacy pieces of Solana’s chain like <a href="https://blockworks.co/news/solana-proof-of-history">proof-of-history</a> (PoH), Tower BFT and gossip-based vote propagation.



The average Solana user has no idea what these are, nor do they need to care, so I&#8217;ll try to keep it simple.&nbsp;



PoH and Tower BFT are the twin core pieces of Solana’s architecture today that allow validators to order blocks without having to interact.&nbsp;&nbsp;



Think of PoH as a pre-consensus cryptographic stopwatch that timestamps blocks. Those timestamps serve as a shared clock which the Tower BFT algorithm then serves up to validators for commitments. This way, the Solana blockchain is able to keep producing blocks without requiring a synchronous consensus round as is typical with traditional chains.



This protocol design has served Solana well, but there are trade-offs.



For one, it creates an overhead cost for voting transactions, which makes up something like 70% of Solana’s onchain transactions (see gray chart below). Vote transactions are distinctly separate from the kinds of transactions that ordinary users send to use the chain; they are an attestation that validators have to pay to lock in their commitments for Tower BFT, or a cost of doing business.



<figure class="wp-block-image"><img decoding="async" src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXdYseNq0kL6YtWTBAaXpsynKarYP0qNRKRVMx6BszJ81PZ7SztPeA91Lo-03As6z_rf6ZAkBp2qFGUXkP2sFgM6Hb0RCDdHoHOZyCq_58jiO0_MKGZmNj4hiPu0ZKoPVrIVjrP-Iw?key=g93vGr6mMwKrQnYKnL2EnQ" alt=""/></figure>



This has created something of a longstanding pernicious problem for Solana validators.



The bigger the stake of a Solana validator, the more earning opportunities they are given to produce blocks. But every validator, regardless of the size of their stake, pays the same fees to vote.



This “fixed cost, variable income” economics results in a situation where large validators end up with a greater stake over time, in effect centralizing network stake from smaller to large validators. Network decentralization suffers because it’s unprofitable to run a validator unless you’re coming in with deep pockets.



<figure class="wp-block-image"><img decoding="async" src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXd2dpfuDdqfXstqBVAXWT6TUF_jb5rudhGATKOGQGjrm3H4zsnkzfAmXG7o7xGuanieI09GUaaDp7ciIqvqEiQTIdECBbh0MyOdss4kF-y8997cBuVVAZaHwyT_ml_0ZIVzWj4w?key=g93vGr6mMwKrQnYKnL2EnQ" alt=""/></figure>



(That also explains why the Solana Foundation has an <a href="https://solana.org/delegation-criteria">initiative</a> to subsidize smaller validators in their first year of operations.)



Alpenglow aims to nip this problem in the bud by getting completely rid of voting costs. That’s where its new components, Votor and Rotor, come in.



Votor shifts validator voting off-chain, but records the aggregate as a compact onchain certificate. Alpenglow therefore replaces per-slot vote transactions with a fixed fee, compressing consensus into one-two rounds to achieve its target finality of 100-150ms.



Rotor, on the other hand, is an improved block propagation protocol that replaces Turbine. It uses a simpler relay scheme to reduce the number of times data jumps from node to node, shaving off end-to-end network latency.



Votor and Rotor jointly underpin Alpenglow’s promised “20+20” resilience model. Under this new model, the Solana network preserves safety and liveness even with 20% of stake controlled by malicious validators and an additional 20% offline.



If this is still all too confusing, just picture AI Peter Griffin dancing through a Minecraft map — somehow, consensus starts to make sense.



<figure class="wp-block-embed is-type-rich is-provider-twitter wp-block-embed-twitter"><div class="wp-block-embed__wrapper">
<blockquote class="twitter-tweet" data-width="550" data-dnt="true">solana alpenglow in less than 100 seconds (brainrot version) <a href="https://t.co/QPtHd5QQct">pic.twitter.com/QPtHd5QQct</a>&mdash; doppelbanger (brainrot lead) (@doppelbanger_gm) <a href="https://twitter.com/doppelbanger_gm/status/1958478061692707100?ref_src=twsrc%5Etfw">August 21, 2025</a></blockquote><script async src="https://platform.twitter.com/widgets.js" charset="utf-8"></script>
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Solana validators commence vote on landmark Alpenglow consensus protocol

Shaunda Devens

This is a segment from the 0xResearch newsletter. To read full editions, <a href="https://blockworks.co/newsletter/0xresearch" target="_blank" rel="noreferrer noopener">subscribe</a>.



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Solana’s consensus stack, proof-of-history sequenced with TowerBFT, has always delivered faster block times than competitors. But finality still sits around <a href="https://www.helius.dev/blog/solana-commitment-levels">10-20 seconds</a>, far from the <a href="https://blockworks.co/news/nasdaq-on-solana-opening-bell-sol-strategies">Nasdaq-level</a> latency Solana aspires to.



<a href="https://forum.solana.com/t/simd-0326-proposal-for-the-new-alpenglow-consensus-protocol/4236?utm_source=chatgpt.com">SIMD-0326 (“Alpenglow”)</a> proposes cutting finality to ~100-150ms by moving validator voting off-chain. Today, validators continuously post votes onchain to signal fork choice, and these votes dominate throughput despite carrying no user value.&nbsp;



<figure class="wp-block-image"><img decoding="async" src="https://lh7-rt.googleusercontent.com/docsz/AD_4nXep-a2mLDrML2PqhV7_I3cZcXheUNUMCvLGzKzNsibs7NUiDFVpVXsJR5spqn8eQ4GI4iiaRDP7IDBz3JBNePOjlWx8B1i0dDBywoA5NIPArzpJp4X9RKow_rlOo7Fn5q8__6meyw?key=bDbckPlQ3bo3NOrYyaM8OA" alt=""/><figcaption class="wp-element-caption">Source: <a href="https://solscan.io/analytics#txs">SolScan</a></figcaption></figure>



Under Alpenglow, validators instead pay a fixed “Admission Ticket” of 1.6 SOL per epoch, burned to the network. Leaders then gather votes off-chain through a component called Votor, compress them into certificates, and write those certificates onchain. The result is a swap: Millions of low-value vote transactions are replaced by one predictable fee per validator, lowering consensus overhead by ~20% and freeing blockspace for user activity.



The design also adjusts fault tolerance. TowerBFT today remains live unless more than 33% of stake is adversarial. Alpenglow introduces a “20+20” model, where the chain stays live with 20% malicious stake and another 20% offline. For applications like DeFi, specifically perpetual exchanges like Drift, sub-second finality transforms Solana from “fast” into a real-time settlement layer.



The economics are still under debate. Smaller validators face a flat 1.6 SOL per epoch fee regardless of stake, while reward flows remain undefined. Governance discussions (epochs 833-842) have emphasized the need for a clear rollout path, including sequencing for Alpenglow’s components. Still, if implemented, SIMD-0326 would represent one of Solana’s most significant structural upgrades.



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