Testing Kimi K3 for Rust Code Optimization in 2026
Tested Kimi K3 for Coding
I tested the new Kimi K3 model to optimize a complex Rust function I had struggled with. After setting it up in OpenCode, Kimi K3 suggested and flawlessly implemented a SWAR optimization, boosting performance by 2%. The process took 15 minutes and cost about $1, proving the model delivers near-frontier quality for real-world coding tasks.
Kimi K3 both decided on an appropriate optimization, and implemented it with no errors—it seems to me that Kimi K3 could well be a frontier-level model as advertised.
- codemog
Should have given the other frontier models a chance too? What if Fable or GPT-5.6 would have found a 30% speed up? Not like a sample size of one means much though.
- garciasn
Saving you a click:
> I decided to try it out and see if it could optimize my Rust program.
> Kimi K3 had 2 recommendations, and I decided to have it pursue the SWAR optimization—SIMD Within a Register. With SWAR, a single 64-bit value is treated as 8 eight-bit values—so we can handle 8 u8 values (single-byte) at once.
> Kimi K3 took about 15 minutes for the task, and it completed it perfectly. I found the optimization sped up the program by 2%.
> It cost about $1 for the tokens on OpenRouter.
- kxxx
Author couldn't be bothered to compare any other models? ok man