Gas Optimizations

[code423n4]

x = x + y is more efficient than x += y, same for x = x - y and x -= y

RRUtils.sol
BytesUtils.sol

variables that are assigned as zero should be left unitialized

RRUtils.sol
DNSSECImpl.sol
BytesUtils.sol

Potencies of 2 (and multiples of 2) i.e. 2**(number) can be converted into left-shift minus one 2<<(number - 1) for a more efficient operation

#L219
#L69

Multiplications by multiples of 2 can be turned into a left shift which uses cheaper opcodes

#L316

require() statements using && operators should be split into two different require() operations.

#L268

Use a more recent version of Solidity

NameWrapper.sol

This is an important mention because not only v0.8.15 has introduced better heuristics for yul optimization, relevant for the assembly codes in here, but also because the developers have compiled this very project and found a decrease in 4.89% in deployment costs and 0.29% in runtime gas. Source

++i iterators are more efficient than i++ iterators.

RRUtils.sol
DNSSECImpl.sol
ETHRegistrarController.sol

uint256 iterators should be left unchecked {} as there's no risk of overflow

RRUtils.sol
DNSSECImpl.sol
ETHRegistrarController.sol

<array>.length loop comparisons being iterated one by one can use the != operator instead of <

RRUtils.sol
DNSSECImpl.sol
ETHRegistrarController.sol

#L93

!= 0 comparisons are more efficient than > 0 for unsigned integers

#L245
#L93

require() statements will consume less gas if the revert string contains less than 32 characters

ETHRegistrarController.sol

Using unsigned integers other than uint256 incurs overhead costs

#L47

Remove unused error message

#L25

Functions that necessarily revert when called by normal users can be set as payable

DNSSECImpl.sol

Use calldata for read-only arguments for external functions

DNSSECImpl.sol