Yeah if my co-worker can't start figuring out why the code is slow, with a reasonable reference to what the code in question is, that is a knock against their skills. I would actually expect some ideas as to what the problem is just off the top of their heads, but that the coding agent can't do that isn't a hit against it specifically, this is now a good part of what needs to be done differently.

The suggestion to tell the agent to do performance analysis of the part of the code you think is problematic, and offer suggestions for improvements seems like the proper way to talk to a machine, whereas "hey your code is slow" feels like the proper way to talk to a human.

As someone who leads a team of engineers, telling someone their code is slow is not nice, helpful or something a good team member should do. It’s like telling them there’s a bug and not explaining what the bug is. Code can be slow for infinite reasons, maybe the input you gave is never expected and it’s plenty fast otherwise. Or the other dev is not senior enough to know where problems may be. It can be you when I tell you your OOP code is super slow, but you only ever done OOP and have no idea how to put data in a memory layouts that avoids cpu cache misses or whatever. So no that’s not the proper way to talk to humans. And AI is only as good as the quality of what you’re asking. It’s a bit like a genie, it will give you what you asked , not what you actually wanted. Are you prepared for the ai to rewrite your Python code in C to speed it up? Can it just add fast libraries to replace the slow ones you had selected? Can it write advanced optimization techniques it learned about from phd thesis you would never even understand?