Rust/C++ lambda cold starts are in the 15ms ballpark, it is very unlikely that you are going to get anything much faster than that. Spinning up firecracker vm just inherently takes some time no matter what you run inside it.

https://maxday.github.io/lambda-perf/

I can't bring myself to use Rust for AWS Lambda since the runtime is still marked as "experimental".

>The Rust runtime client is an experimental package. It is subject to change and intended only for evaluation purposes.