She slow to the point where it takes her three hours to do a job that should take less than one. She makes a lot of simple mistakes, and no matter how often I correct her, she still makes them (or I'll show her how to do something more efficiently and she'll promptly 'forget'). On the other hand she's great at customer service, but she's been there longer than I have, and none of my other employees seem to have these issues. I know she thinks I single her out because I pick up on her mistakes 'more', but the truth is they're things I shouldn't have to pick up on.
Srs & non-srs answers welcome.