Re: It's getting annoying..
I am still working my way toward shodan but I understand a bit of what you are feeling. We have a flood of new people in our small dojo and yep all of the more experienced students are expected to pair up with and help the beginners. Yep sometimes you just want to work out hard and sometimes it is frustrating to work with someone who does not know where to put his/her hands or feet let alone how to do a technique.
But you know I have found that I learn a whole lot of things while trying to find a way to teach someone what they need to do. I notice things and become aware of details I had not really thought of for a while if at all. There is a lot of value in working with brand new people, remembering that we to were once brand new. Teaching new people has helped me to be much more aware of what I am doing in my own training.
Luckily for me our little dojo has classes set aside that are only for the more advanced students so we do get to train hard too and sometimes sensei will specifically pair up a couple of advanced students and give them something more complex to work on while he/she is working with beginners on something else. Maybe you should ask your sensei to do something similar if he has not already.
Remember that the dojo needs fresh blood. You need those beginners especially for a small dojo that is just making ends meet. You don't want to chase them away by your resentful attitude. Trust me they can feel that from you and it will discourage many of them from continuing.
Talk to your sensei about your frustrations if you are able and even ask some of the more advanced people to work out with you hard after class or use one of them for demo and really throw them around to show your new student what will be possible for them in the future. Just this week I really was having a fierce need to just really train hard and get thrown around and I made that need known and had no problem finding a number of people more than happy to fill that need for me. My own teachers took up that task quite happily.
One of the things my teachers have made sure to tell us from early on. We should expect that as we progress we will have more responsibility to help those behind us to learn and once shodan has been reached we ought to expect that we will be required to take up some of the responsibly in teaching. I have already been required to bow in and lead class a couple of times. I look at those assignments as a mark of my teacher's trust in me and as a privileged assignment rather than an onerous and distasteful chore.