Should I contact potential referees for a job application?
As I don't know about the academic practice in Switzerland, I may contribute some theoretical thoughts. 

What is the benefit of having people evaluate one's achievements or products in general when they do not know you in person? I guess the key is to have them unbiased. Then it will be better to name them without contacting them in advance.

A drawback may be, that if you name a person who has no time or interest in judging your scientific output it may look unprofessional if you provided their name without checking for their willingness to do that task.