Even if you invoke your lambda function to warm it up in anticipation of traffic, you'll still hit cold starts if the lambda needs to scale out; the new machines are exposed to inputs "cold." Those crazy patterns trying to warm the lambda up are really crazy if you think about it because no one is using them is really aware of the underlying process(es) involved.

"Why are you throwing rocks at that machine?"

"It makes it respond more quickly to actual client requests. Sometimes."

"Sometimes?"

"Well, most the time."

"Why's that? What's causing the initial latency?"

"Cold starts."

"Yeah, but what's that mean?"

"The machine is booting or caching runtime data or, you know, warming up and serverless. Anyway, don't think about it too much, just trust me on this rock thing. Speaking of which, I got to get back to bastardizing our core logic. Eddie had great results with his new exponential backup rock toss routine and I'm thinking of combining that with a graphql random parameter generator library that Ted said just went alpha this afternoon."

If initial startup time - and long periods of non usage - is an issue, wouldn't a permanently running VPC for the initial load be a better solution?

Clever uses of dependency injection without reflection (think dagger not spring) and reducing code size as much as possible can give you fairly fast cold start times with a Java execution environment. Bloated classpaths and reflection filled code will destroy your initialization time.

And by "…Go the fastest." I assume you mean compiled languages.