Use of UIKit in unit testing performance affected?

In general, is there any performance penalty induced, if one were to import UIKit in unit testing target in an iOS project? I have no objective way to say if this is true or false. I would assume that potentially this could be true. On the other hand, I was wondering, the UIKit is kind of omnipresent in iOS, it therefore could already be 'preloaded', and not induce an extra performance penalty?