Is Solana finality really 150 ms after Alpenglow?
Short answer: In the first 15 hours of a 7-day test, a public Solana RPC node saw blocks become final a median 222 ms after it had the whole block, and 95% within 512 ms. That is about 58 times faster than the old 12.8 seconds, but above the 150 ms target. The verdict is due on 2026-10-29.
Alpenglow replaced Solana’s TowerBFT voting with a new protocol, Votor, on 2026-10-21 (epoch 1064). Launch coverage put finality at about 150 ms, down from about 12.8 seconds, and one reading of 202 ms from the Solana Foundation’s dashboard was reported on launch day (Altcoin Buzz, Genfinity). A single reading says little about a whole week, so we are timing every block.
How we measure
- Source: the Solana Foundation’s public RPC endpoint. For each slot it publishes timestamped events: first piece of the block received, block complete, and the moment the node treats the block as final.
- F = time from “block complete” to “final”, per slot, on the node’s own clock.
- Every slot, around the clock, for 7 days from 2026-10-22 10:15 UTC.
- The rule was written and timestamped before recording started: HOLDS if the median F is at or below 150 ms and the 95th percentile at or below 300 ms. Otherwise FAIL.
Interim results
15 hours, 246,056 blocks, updated 2026-10-23. Interim numbers can move; the verdict uses all 7 days.
| Measure | Value |
|---|---|
| Median F | 222 ms |
| 95th percentile F | 512 ms |
| 99th percentile F | 613 ms |
| Blocks final within 150 ms | 9% |
| First piece of block to final, median | 495 ms |
| Slot time | 212 ms |
| Day (UTC) | Blocks | Median F | 95th percentile |
|---|---|---|---|
| 2026-10-22 | 231,003 | 224 ms | 516 ms |
| 2026-10-23 | 15,053 | 214 ms | 413 ms |
What this does and does not show
- This is finality as an app reading a public RPC node sees it. Validators see votes sooner, so a validator-side figure is likely lower.
- One vantage point. The two other free endpoints we tried do not publish these events.
- Block propagation was not part of this first Alpenglow step, so a block still takes about one slot (212 ms) to arrive in full. Counted from the first piece of the block, finality is a median 495 ms.
- Even on the interim numbers, a payment or trade on Solana becomes final in about 0.2 seconds instead of about 12.8. The test is about the size of the claim, and the improvement is real either way.
Verdict
PENDING until 2026-10-29. The final numbers and the verdict will replace this section on that day, whichever way they fall. Not financial advice.