Agentic LLMs like Opus 4.5 shown to auto-optimize Rust code 2x-20x faster

A developer tested whether repeatedly asking modern agentic LLMs to improve code could yield genuine performance gains, this time using Rust rather than Python. After months of experimentation following the release of Opus 4.5, the author found that these models can produce Rust code significantly faster than current state-of-the-art implementations, provided they are given proper constraints and guardrails.