Solana testnet has reached a 250-millisecond slot time, clearing the fourth of five stages in the SIMD-0525 schedule that aims to cut slots from 400ms to 200ms. Anza CEO Brennan Watt posted the result on August 13, and 19 minutes later shared a second measurement showing 10,000 transactions per second at 236ms under synthetic load (generated test traffic rather than live user activity). The testnet milestone follows earlier 350ms and 300ms checkpoints reported on August 7 and August 11. Under the feature-gated process, each step can advance only if the previous one maintains acceptable block skip rates, before any eventual stake-weighted supermajority vote on mainnet. Official Solana documentation says the performance gains behind the reductions come from Turbine (Solana's block propagation layer) and the Replay pipeline. One step remains before the 200ms target. Separately, Anza plans to activate the Alpenglow consensus upgrade on September 28 through Agave 4.3, according to a release schedule published August 13.