Only using SafeMath when necessary can save gas

[code423n4]

Handle

WatchPug

Vulnerability details

or the arithmetic operations that will never over/underflow, using SafeMath will cost more gas.

For example:

https://github.com/code-423n4/2021-11-yaxis/blob/146febcb61ae7fe20b0920849c4f4bbe111c6ba7/contracts/v3/alchemix/Alchemist.sol#L623-L637

if (_totalCredit < _amount) {
    uint256 _remainingAmount = _amount.sub(_totalCredit);
    // ...
}

_amount - _totalCredit will never underflow.

Recommendation

Change to:

if (_totalCredit < _amount) {
    uint256 _remainingAmount = _amount - _totalCredit;
    // ...
}