Lower than uint256 size variables are less gas efficient. E.g. using uint8 does not give any efficiency, actually, it is the opposite as EVM operates on default of 256-bit values so uint8 is more expensive in this case as it needs a conversion. It only gives improvements in cases where you can pack variables together, e.g. structs. Here is the example where uint256 would be more efficient:
for (uint8 i = 0; i<tokens.length; i++)
Shadowfiend
commented
2 years ago
Handle
pauliax
Vulnerability details
Impact
Lower than uint256 size variables are less gas efficient. E.g. using uint8 does not give any efficiency, actually, it is the opposite as EVM operates on default of 256-bit values so uint8 is more expensive in this case as it needs a conversion. It only gives improvements in cases where you can pack variables together, e.g. structs. Here is the example where uint256 would be more efficient: for (uint8 i = 0; i<tokens.length; i++)
Recommended Mitigation Steps
for (uint256 i = 0; i<tokens.length; i++)