Solana transaction ranking uses fee-to-cost ratio, not fee size alone

Solana block producers rank transactions by dividing the leader's reward by the transaction's compute-unit cost, not by the raw priority fee amount. This means two transactions paying identical lamports can land in vastly different queue positions depending on how much block space each consumes. Key cost drivers include the compute-unit execution limit and a loaded-accounts-data reservation, both of which default to their maximum values if developers do not explicitly set them. A worked example shows that trimming a swap's compute limit from 1.4 million to 80,000 units and capping loaded-data size raises the transaction's rank roughly 17 times while keeping the same lamport bid. Since 31 August 2026, ties in priority score are broken by arrival time, making microsecond-level submission speed a meaningful tiebreaker.