Gas Optimizations

[code423n4]

Gas Report

G-01: use unchecked when incrementing the loop's variable

Since the loop's variable can't overflow in most circumstances, you can safe gas by incrementing it inside a unchecked block:

for (uint i; i < length;) {
    unchecked {
        ++i;
    }
}

e.g.

• https://github.com/code-423n4/2022-07-ens/blob/main/contracts/ethregistrar/StringUtils.sol#L14
• https://github.com/code-423n4/2022-07-ens/blob/main/contracts/ethregistrar/ETHRegistrarController.sol#L256

G-02: Don't allow the user to send more ETH than necessary allows you to remove the refund logic

In the ETHRegistraryController contract, you allow the user to pay more than necessary for the registration. Any surplus amount is then refunded.

If you force the user to pay the exact amount, you can remove the refund logic and thus save gas.

• https://github.com/code-423n4/2022-07-ens/blob/main/contracts/ethregistrar/ETHRegistrarController.sol#L138
• https://github.com/code-423n4/2022-07-ens/blob/main/contracts/ethregistrar/ETHRegistrarController.sol#L183

[jefflau]

G-02: Don't allow the user to send more ETH than necessary allows you to remove the refund logic

Intended behavior because the amount of ETH varies based on the oracle.