Aptos has officially transitioned its Layer-1 blockchain to the Block-STM v2 engine as the default system for transaction processing. This upgrade, which was first announced in October 2025, is now active following updates in 2026 that included performance optimizations and consistency fixes.
The new engine utilizes optimistic concurrency control to execute transactions across multiple processor threads simultaneously. When conflicts occur, the system re-executes only the specific transactions involved, ensuring a deterministic result without requiring manual intervention from developers or users.
Unlike the previous version, Block-STM v2 performs parallel execution dynamically. It eliminates the need for upfront access lists or dependency declarations, simplifying the integration process for decentralized applications.
While the original Block-STM v1 achieved approximately 170 000 transactions per second in 2022 benchmarks, the v2 update is designed to scale across up to 256 processor cores. The primary goal of this transition is to improve performance for high-frequency DeFi workloads.
