Measure whether an Ethereum access list saves gas
An access list makes selected accounts and storage slots warm before a transaction executes. Every listed entry has an upfront gas cost, including entries the code never visits.
Compare the same simulated call
Estimate a representative call twice at the same block using the same sender, value and calldata. First omit the access list. Then include the candidate addresses and slots. One address and two slots add the following intrinsic cost under EIP-2930.
2400 + 2 × 1900 = 6200 gas
The 6,200 gas is the cost of declaring the entries. Savings come from accesses that would otherwise be cold. Adding the transaction destination can cost gas even when that address is already warm at execution start.
Check the branch that really runs
Try inputs that take different contract branches. An access list tuned for the common path can increase the cost on another path. Gas estimates depend on client simulation and state, so compare with an actual receipt when such a transaction has already been executed. eips.ethereum.org EIP-2930