Almost vomit my blood out

I almost vomit my blood out coaching one new colleague on some work process. Even took pains to explain and demonstrate step by step. She can be quite forgetful, so i slowly told her the step by step. She took almost whole afternoon to do that piece of work. I have to admit that maybe my tone may sound harsh, but most earnestly wanted my colleague to learn the ropes as quickly as possible. There were still lot of stuff for her to learn and take responsibility.