Thomas Piellard enhanced the Poseidon2 hashing algorithm in the Consensys/linea-monorepo by introducing lazy reductions to minimize addmod operations, directly improving gas efficiency for on-chain cryptographic computations. He merged the sbox and addroundkey steps, streamlining the hashing pipeline to reduce computational overhead and improve throughput. Working exclusively in Solidity, Thomas focused on performance tuning, code refactoring, and increasing maintainability and testability of the smart contract codebase. His work addressed ongoing cryptographic optimization goals for the project, with all changes consolidated in a single, traceable commit to support future maintainability and clear documentation of the engineering improvements delivered.