Disclosure: I'm the maintainer of the open source project - openfaas which this blog post talks about. It also covers other FaaS frameworks and why we see a "cold start" even when using Kubernetes as our platform.
Also it feels to me like FaaS is good when someone else is running the infrastructure (so you really don't have to know about the underlying infrastructure). Why are people self hosting this? Is it for local test platforms before deploying to a managed FaaS?