250ms slot activation will await activation at epoch 1035, while the feature will be active at epoch 1036 and go live at epoch 1037.
The “250ms slots” make Solana closer to its ultimate goal: a 200ms slot time, as Anza pointed out in its X post: “1 more step to 200ms.”
250ms slots activation now pending on mainnet-beta.
400 → 350 → 300 → 250ms
Reminder, SIMD-0525 features take effect one epoch after they activate thus will go live at the epoch 1037 boundary ~05:01 UTC, Friday Sept 18.
– epoch 1035: pending activation
– epoch 1036: feature…— Anza (@anza_xyz) September 16, 2026
Solana is reducing its slot times in stages from 400ms to 200ms: 400ms → 350ms → 300ms → 250ms → 200ms. This was first discussed in SIMD Discussion 469 and then formally proposed and approved in SIMD-0525.
Each 50ms reduction has its own feature gate and activates independently. The steps are spaced out to give core developers time to monitor cluster performance between activations.
The 350ms and 300ms reductions are active on mainnet, with feature activations of 250ms and 200ms already activated on devnet and testnet. 250ms is now pending mainnet activation.
1 more step to go
Activation dates for the 200ms slot time, the last reduction, are still being determined by core developers.
Shorter slots mean more blocks in the same wall-clock time, and at 200ms the network produces twice as many blocks per day as it did at 400ms.
Solana believes that decreasing slot times will allow the network to be more competitive with other blockchain protocols. This change also sets a precedent for future latency improvements.
The upgrade is beneficial to all: users will have faster confirmation times for their transactions, and market makers will be able to offer tighter spreads. Validators will have shorter epochs (a Solana epoch is a fixed 432,000 slots, so it takes about 36 hours at today’s 300ms, down from roughly 48 hours at 400ms, and will take about 24 hours once 200ms is activated), which means they are rewarded faster for adopting the performance improvements on Mainnet.
