I have a feeling AWS lambda's hypervisor has a lot of overhead, and simply making your workload smaller/lighter has a very noticeable reduction in execution time (cold start is <10ms on most of our GO lambdas).

re: full serverless:

I mean, try for yourselves but unless you're running an echo statement, you'll probably be hard pressed to get lower than this. Some early experiments with Rust showed 5x that, and that is as close to GO as I would dare to compare.