What is the difference between configurations that are thrown to plugins in kong.yml and those specified in kong.conf?

[svyatoslavratov]

Hello!

I created a system with dynamically customizable kong.yml due to js-yaml and variable injection. I end up injecting my environment variables into kong.yml. This allows me to use basic configurations and not do copypaste.
But my kong.yml quickly becomes large and there are a lot of similar configurations. Although I don't work directly with kong.yml, it is generated automatically by my system.

I have some questions:

1. What is the difference under the hood between the variable definition in kong.conf and kong.yml?
2. Does the final size of the kong.yml file have an effect on performance? Or does it affect nginx in any other way?