Dear DeveshCH, your post does not reveal much for any advice; at least I cannot gather from your reply, "appointed on senior designation." You were asked to explain what the work, job, or responsibilities of that employee were, and what type of work—manual, clerical, supervisory, officer, operational, etc.—was given to him. Furthermore, what was expected from him by management and how he has performed are the basic questions.
Merely saying performance is not satisfactory does not help anybody. You will have to be specific in putting charges on the employee, and further, you must be able to justify or prove (very popular among HR Fraternity) those charges of slow performance. However, mind you, slow performance of an employee is not misconduct, but willful or intentional slowing down of performance is certainly a serious misconduct.
So, one should always be careful in leveling charges of slow performance against an employee.