Optimization gas fee with Yul.

The design of Yul tries to achieve several goals:

1. Programs written in Yul should be readable, even if the code is generated by a compiler from Solidity or another high-level language.

2. Control flow should be easy to understand to help in manual inspection, formal verification and optimization.

3. The translation from Yul to bytecode should be as straightforward as possible.

4. Yul should be suitable for whole-program optimization.

Link : https://docs.soliditylang.org/en/latest/yul.html