The Alpenglow upgrade will replace Solana's existing voting system, aiming to reduce transaction finality to approximately 150 milliseconds, a 40-fold increase in speed. This involves moving validator voting off-chain and bundling votes into certificates. The overhaul, which also cuts validator vote fees by about 60% (from 2 SOL per day to 0.8 SOL per epoch), follows months of testing, including a failed migration and rollback on the test network.