Gas Optimizations

[code423n4]

++i is cheaper than i++

Use prefix increment instead of postfix increment.

Unnecessary checked arithmetic in for loops

The i++ part of for loops can be surrounded by the unchecked keyword to save gas. For example:

for (uint256 i = 0; i < 10; i++) {
...
}

can be optimized to:

for (uint256 i = 0; i < 10;) {
...
unchecked { i++; }
}

!= 0 is cheaper than > 0 (unsigned integers)

When dealing with unsigned integers the != 0 comparison is equivalent to > 0 comparison. It is also cheaper, therefore you should use it instead.

Cache Array Length Outside of Loop

You can optimize for loops that iterate over array elements by caching the array length in a local variable. This will reduce the number of MLOADs and will save gas. For example:

for (uint256 i = 0; i < array.length; i++) {
...
}

can be optimized to:

uint256 length = array.length;
for (uint256 i = 0; i < length; i++) {
...
}

Repeated computation of the same value in AuraLocker._processExpiredLocks()

That function computes length - 1 multiple times. The result can be computed once and be cached in a local variable in order to save gas.

Repeated access to the current array element in for loops

Many for loops that iterate over array elements access the current element (array[i]) more than once in each iteration. This element can be accessed only once (and be cached in a local variable) in order to avoid the additional array-boundaries check that Solidity performs with each array access, and save gas.