HR people in the UK use 'performance management' as a euphemism for a kind of legal constructive dismissal.

1) Their attitude stinks but nothing specific that can be picked up in a disciplinary on its own

2) They have been in the job for a few years, and their old manager never recorded the behaviour problems

3) Their role is not redundant

So to get them out you meet regularly, set short term goals, and be really picky about not meeting them. The whole thing is designed to make the staff miserable so they leave or get sacked for missing the goals, whilst building up a substantial volume of paperwork supporting a legal defence at tribunal.

Or less cynically it allows the staff to understand what is expected of them, so they perform better. This never works IMHO