Comment by HarHarVeryFunny

If you look at Anthropic's recent kernel optimization challenge, and the human leaderboard, humans are soundly beating Claude's best attempt.

I think the reason, as parent suggested, is that LLMs are great at composition (mash-ups/regeneration - this is essentially what they are trained to do), and not so great at innovation. How well they can do relative to a human, on a low level optimization problem, is going to depend on degree of similarity of the problem to things they were trained on and/or have access to.