Solana Alpenglow upgrade will be activated on October 21 Alpenglow mainnet test version will be activated at 14:50 UTC on 10/21 (starting from epoch 1064). Transaction finality reduced from approximately 12.8 seconds to about 150 milliseconds—about 85x faster, a 98.8% decrease. This is the biggest consensus mechanism change since Solana's launch, taking about 18 months.