Vibe Coding Is Challenging

A developer reports that using Crouton Alpha to rewrite a hot Rust loop produced code that was slightly faster than previously hand-optimized code, but only after several failed attempts that showed promise before the concept was correct. The developer argues that vibe coding—prompting an LLM to generate code—is difficult in complex programs where a small mistake can be a catastrophe, and that testing, prompting and understanding the program's goals must come together rather than mindless prompting.

I have some Rust code that is hot and I have spent time hand-optimizing it in the past. It frustrated me because I could not make it any faster. Recently I decided to try a new approach—using Crouton Alpha to write a new loop structure for the code. The first attempts did not work completely, but they showed promise. Finally I got the concept correct and it worked perfectly, and performance was even slightly improved over the previous hand-tuned code. I feel like vibe coding —prompting an LLM to generate code—is difficult when done in certain situations. Some programs are complex and even a small mistake can be a catastrophe. When I see people vibe coding on the Internet, I will keep this in mind—just because someone is using AI to generate code does not mean the job is easy. Many pieces must come together—testing, prompting, understanding the program's goals—it is not just mindless prompting.