Gulf Stream is Solana's transaction forwarding and caching protocol. Because Solana's leader schedule is known in advance — determined by Proof of History — Gulf Stream routes incoming transactions to the expected next validator before their slot begins.

This pre-routing eliminates the traditional mempool model used by blockchains like Ethereum, where transactions wait in a shared queue. Instead, transactions are forwarded to where they are most likely to be processed, reducing confirmation latency.

Gulf Stream allows the Solana network to handle tens of thousands of pending transactions efficiently, with validators caching upcoming transactions and processing them immediately when their slot begins.