One more solution is make the underperformers as out performing employees with training instead of recruiting new employees, waiting for them and giving training to them. Also a scale to 1-5 rating is wantedly so that whoever gets 1 and 2 should quit. This doesn't mean that he is an underperformer but his relative performance is less.If someone gets 1 or 2 they are the victims and doesn't know how to apply soap to bosses.