Worked on performance optimization and codebase simplification across two projects over a two-month period. In the oxc-project/oxc repository, refactored the oxc_parser crate’s Token storage by packing multiple properties into a single u128, reducing memory usage and improving cache locality while maintaining backward compatibility. This involved low-level programming in Rust and the introduction of bitwise accessors for efficient property retrieval. Later, contributed to atlassian-labs/atlaspack by removing Flow type checker dependencies and related configurations, streamlining the JavaScript codebase and preparing it for a new type-checking strategy. Focused on maintainability, type checking, and performance tuning throughout both projects.