I get what you're saying, it sucks training the new guy. It is however, the sign of a good/great programmer/performer to be able to train other people. Also, frankly, it just has to be done. Companies don't want to lock their knowledge into a few good people.
You take on the challenge of efficiently "getting your assigned work done". I'd challenge you to take on the task of teaching others with the same mentality you approach your "regular" work. Do it as efficiently and productively as possible. Then when you're done, go about your day.