Gas is too high in contract

Question

I have the following stake function that whenever I call it uses almost 100.000 gas. I did the usual stuff optimizing the code to use less gas like using structs and uint256, but the gas price is still abnormally high.

Gas:101721 Transaction cost:101721

function stake(uint256 amount) external updateReward(_msgSender()) {
    require(amount > 0, "Cannot stake 0");
    totalStakeAmount = totalStakeAmount.add(amount);
    User storage _user = userInfo[_msgSender()];
    _user.stakeAmount = _user.stakeAmount.add(amount);
    emit Staked(_msgSender(), amount);
}

function unstake(uint256 amount) public updateReward(_msgSender()) {
    require(amount > 0, "Cannot withdraw 0");
    User storage _user = userInfo[_msgSender()];
    totalStakeAmount = totalStakeAmount.sub(amount);
    _user.stakeAmount = _user.stakeAmount.sub(amount);
    IERC20(stakeToken).safeTransfer(_msgSender(), amount);
    emit Unstaked(_msgSender(), amount);
}

Answer 1

Your contract looks like a Synthetix derivative. If that's the case, then updateReward is here: https://github.com/Synthetixio/synthetix/blob/develop/contracts/StakingRewards.sol#L152

The Synthetix contract uses a complicated staking algorithm. That means it's not very cheap to use. But the good thing is that the cost doesn't go up as the number of stakers goes up, so the usage costs are constant. This makes it truly scalable. You simply have to accept that or use some other staking algorithm - although I doubt there are many more efficient ones.