Use existing memory version of state variables

[code423n4]

Handle

ye0lde

Vulnerability details

Impact

Using existing local variables instead of reading state variables will save gas by converting SLOADs to MLOADs.

Proof of Concept

_nstReserve can be used here:
https://github.com/code-423n4/2021-11-nested/blob/5d113967cdf7c9ee29802e1ecb176c656386fe9b/contracts/NestedBuybacker.sol#L69

_feeSplitter can be used here:
https://github.com/code-423n4/2021-11-nested/blob/5d113967cdf7c9ee29802e1ecb176c656386fe9b/contracts/NestedBuybacker.sol#L76

_burnPercentage can be used here:
https://github.com/code-423n4/2021-11-nested/blob/5d113967cdf7c9ee29802e1ecb176c656386fe9b/contracts/NestedBuybacker.sol#L84

_maxHoldingsCount can be used here:
https://github.com/code-423n4/2021-11-nested/blob/5d113967cdf7c9ee29802e1ecb176c656386fe9b/contracts/NestedRecords.sol#L173

Tools Used

Visual Studio Code, Remix

Recommended Mitigation Steps

See Proof of Concept

[adrien-supizet]

We believed it would be true, after testing it actually shows no difference.

[alcueca]

It should be true, even after the London fork. Reading from memory costs a minimum of 100 gas.