How using additional namespaces affects performance?

Questions & Answers
1

I wonder how adding something along the lines of:

using System.Collections.Generic

or

using UnityEngine.UI

affects performance or size of the project. Is it significant?
I ask, because I’d like to change packs of regular variables into dictionaries, but I don’t know if it is worth it.

2

It has zero effect on either the performance or size of a project.