Why would that relationship be there? One CPU cycle is more akin to a single internal reaction in a cell. The idea that our brains are *not* doing complex calculations quite a lot is the misconception here. A single CPU cycle is not enough to even begin to do a useful computation, while the human brain can hit a 100-mile fastball with less than a second of brain computation.
The real difference is that a computer AI can be multi-tasking in a way the brain can't. So, even if conversations with the human world would be slow, they could be processed separately, and wouldn't require the "full" attention. (One of the things I would have loved in "Her" is if they showed us this multitasking. At one point, the AI is singing a song, and the lead starts up a conversation. She stops singing and talks, but it would have been funny and alien if she just put her singing into "background music" mode, and then talking while singing. Lack of imagination there.)
We've got modes of communication which are much slower. Consider a book, which was written years ago.
Finally, why ascribe impatience to an AI?