Solana core developer Anza has published a pair of Solana Improvement Documents that would reorder the network's leader schedule by validator geography, with simulations on mainnet data showing a 53% reduction in block production handover delays.

The proposals, SIMD-0674 and SIMD-0675, were authored by Anza researchers Quentin Kniep and Roger Wattenhofer and opened on approximately 29 September 2026. SIMDs are the formal channel for protocol changes on Solana. SIMD-0675 moved to "ready for review" status on 30 September 2026 at 14:27 UTC, while SIMD-0674 remains in draft.

Under the current design, validators take turns producing blocks in an order that is random with respect to geography. Each handover carries latency because the incoming leader must receive the previous leader's work before building on it, and physical distance stretches that wait.

The proposals describe a system in which validators register their geographic location on-chain. The network then uses those registrations to build what the authors call a geo-aware leader schedule, grouping validators into geographic bins that run consecutively so that leadership passes between neighbors rather than across the planet. The design caps each bin at a maximum of 3 consecutive leaders, and a full run through a region lasts approximately 2.4 seconds before the schedule moves on.

The researchers tested the model against mainnet data from epoch 1038, which involved 661 validators. Under existing random scheduling, mean leader handover latency measured 36.2 milliseconds. Under the geo-aware model, that figure dropped to 17.0 milliseconds — the source of the 53% improvement.

For operators weighing revenue implications, the proposals state that stake weights and slot allocations remain unchanged. Every validator keeps its original share of slots; the change reshuffles when those slots occur, not how many each validator receives.

The trade-off is disclosure. Validators that decline to register a location would be excluded from block production and voting, making on-chain registration of a physical location effectively a precondition for participating in consensus. That requirement concentrates operational consequences on validator operators, who would need to decide what location data they are willing to commit publicly.

The timing is tied to Alpenglow, Solana's upcoming consensus protocol, which targets finality of roughly 150 milliseconds — the point at which a transaction is considered permanent and irreversible. Alpenglow was transitioning into testnet and devnet environments in late September 2026, coinciding with the appearance of these SIMDs. Against a finality target measured in the low hundreds of milliseconds, a handover consuming tens of milliseconds represents a meaningful share of the total latency budget rather than background noise.

For builders, lower and more predictable handover latency could tighten the windows in which sequenced transactions and cross-program operations execute, particularly for latency-sensitive applications. For validators, the immediate questions are operational: whether to register, what granularity of location to disclose, and how bin assignment affects peer infrastructure planning.

The near-term milestones are concrete. SIMD-0675 is now open for community review, and SIMD-0674 must clear draft status before the package can advance. Alpenglow's continued progression through testnet and devnet will determine how much pressure the network faces to eliminate delay sources such as handover latency; if the protocol keeps advancing, the review window for these proposals is likely to compress rather than expand.