The process of applying for a new job while you still have a current job will take time, no matter what the process looks like. The hiring company will want a series of interviews, and either a whiteboard, pair program, or code audition. A small project would perhaps take a little more time than these other methods, but should not take take that much longer, provided the hiring company has put some thought into what small projects they are giving to you to audition. If they pay you for your time, that is also respectful.
