You can type something perfectly; you can build a box perfectly square; and, you can copy a paper perfectly. But trying to accomplish perfection at the lectern is a waste of time. Instead of trying to achieve something that is impossible, might I suggest you strive for excellence? Excellence allows for an occasional mistake; perfection doesn't.
Mistakes are made in live performances. It is unavoidable. It is normal. It is natural. Just watch or listen to the news on any given day and you will hear a mistake or two. You won't hear a lot of them, but they do happen. If you think that the only way you can give a great performance is by not making a mistake, then you are placing a pressure on yourself that is unfair - unfair to you as well as your audience.