You can get some nasty cold starts though. Here's a domain I have that doesn't get any traffic (literally zero):

https://imgur.com/a/dVPQYKC

The first hit is brutal. I won't say the CDN since I'm not an expert, but it doesn't take long to go cold (minutes) and once it's cold even the cached hits are 400ms.

Is 400ms really a dramatic reduction in latency?