Gas Optimizations

[code423n4]

• _cliffReleaseTimestamp > 0 is not really needed here:

  require( 
  _cliffReleaseTimestamp > 0 && 
  _cliffAmount > 0 && 
  _cliffReleaseTimestamp <= _startTimestamp
  )

  because _startTimestamp was validated before:

  require(_startTimestamp > 0, "INVALID_START_TIMESTAMP");

• No need to initialize to default values:

  uint112 public numTokensReservedForVesting = 0;

• This is the first assignment to vestAmt:

  if(_referenceTs >= _claim.cliffReleaseTimestamp) {
    vestAmt += _claim.cliffAmount;
  }

  can save a bit of gas by replacing += with just =.

• Can use unchecked maths here and everywhere else where overflow/underflow is not possible:

  if(_referenceTs > _claim.startTimestamp) {
    uint40 currentVestingDurationSecs = _referenceTs - _claim.startTimestamp;

• The duration is re-calculated every time the _baseVestedAmount is queried:

  uint40 finalVestingDurationSecs = _claim.endTimestamp - _claim.startTimestamp;

  even though nor start, nor end timestamps do not change. Wouldn't it be better to store the duration in the Claim struct then?

• Repeated access of storage usrClaim.amountWithdrawn variable:

  require(allowance > usrClaim.amountWithdrawn, "NOTHING_TO_WITHDRAW");
  ...
  uint112 amountRemaining = allowance - usrClaim.amountWithdrawn;

• Can just directly assign usrClaim.amountWithdrawn = allowance:

  uint112 allowance = vestedAmount(_msgSender(), uint40(block.timestamp));
  ...
  uint112 amountRemaining = allowance - usrClaim.amountWithdrawn;
  ...
  usrClaim.amountWithdrawn += amountRemaining;