Solana has activated its first mainnet slot-time reduction since inception, cutting the target from 400 milliseconds to 350 milliseconds under SIMD-0525. The explorer shows the feature live on Mainnet Beta at slot 440,208,000 in epoch 1019, starting a staged rollout toward 200ms via separate 50-millisecond feature gates that can pause if block skip rates rise. Solana Foundation vice president of technology Jacob Creech called the move the network’s first slot-time cut and marked 300ms as the next target. Shorter slots aim to speed confirmations by compressing leader block-building, Gulf Stream handoff, and validator replay and voting, building on Turbine and Replay client gains, without changing ticks per slot, the four-slot leader span, or slots per epoch. The upgrade is labeled a breaking change with indexing work still to be determined, and documentation still cites a 400ms default even as the 350ms gate is active.