Gas optimization for L2 in Blockchain / Solidity

Introduction

Gas optimization helps save money and speed up transactions on Layer 2 blockchains. It makes using blockchain cheaper and faster.

When you want to reduce transaction fees on Layer 2 networks.

When building smart contracts that need to run efficiently on L2.

When sending many transactions and want to save overall gas costs.

When designing dApps that users expect to be fast and low-cost.

When optimizing contract code to avoid unnecessary operations.

Syntax

Blockchain / Solidity

// Example: Solidity function optimized for gas on L2
function add(uint a, uint b) external pure returns (uint) {
    unchecked {
        return a + b;
    }
}

Use unchecked to skip overflow checks when safe, saving gas.

Minimize storage writes and external calls to reduce gas costs.

Examples

This skips overflow checks, which saves gas if you know overflow won't happen.

Blockchain / Solidity

// Using unchecked to save gas
function increment(uint x) external pure returns (uint) {
    unchecked {
        return x + 1;
    }
}

Using smaller data types packs variables into one storage slot, reducing gas.

Blockchain / Solidity

// Packing variables to save storage
contract Example {
    uint128 a;
    uint128 b;
}

Only update storage if the value changes to save gas.

Blockchain / Solidity

// Avoiding unnecessary state changes
function setValue(uint newValue) external {
    if (value != newValue) {
        value = newValue;
    }
}

Sample Program

This contract shows two ways to save gas on L2: using unchecked for addition and avoiding storage writes when not needed.

Blockchain / Solidity

pragma solidity ^0.8.20;

contract GasOptimized {
    uint128 public count;

    // Increment count safely with gas optimization
    function increment() external {
        unchecked {
            count += 1;
        }
    }

    // Set count only if different to save gas
    function setCount(uint128 newCount) external {
        if (count != newCount) {
            count = newCount;
        }
    }
}

Important Notes

Gas costs on L2 are lower but still matter for user experience and cost.

Always test your contract on testnets to measure gas savings.

Use tools like Hardhat or Tenderly to analyze gas usage.

Summary

Gas optimization reduces transaction fees and speeds up L2 blockchain use.

Techniques include using unchecked math, packing variables, and minimizing storage writes.

Testing and measuring gas helps find the best optimizations.