I am not sure of the specifics but I was (once - or maybe more) talking about machine speeds, responses and CPU loads.
I posted stuff and I was asked why I have Apache installed.
I didn't / couldn't answer the question at the time but now I remember.
Looking through the library I often see this at the bottom of the node's page:
This work is licensed under the Apache License 2.0.
So silly me, installed Apache.
I think that is the story to why I have Apache installed.
Or it could be another program I have that says it needs it.