Database to track employee performance
I suggest you read up about database normalization. Here is a good starting point: Third normal form

Definitely do not create one table per employee as management of that database structure will soon become too cumbersome and your application will need to be modified every time a new employee is hired.

I do not know what your business rules are, but assuming that Performance, Quality and Attendance all store different types of data (i.e., different column types) then they should be in separate tables. I could not guess at what primary key you should use without knowing what types of data are stored in those tables.

Can you provide more information?