Maybe depends on region.
I had a tech project with a local ski equipment supplier, and he and my other contacts at his company all spoke in a heavy, really slow going dialect, just like from the movies.
Also, they often tackled problems differently. Slower paced, but more deeply thinking about the next step to be taken.
Collided somewhat with my more agile way of wild brainstorming and quickly start doing stuff...
But that quite certainly might not be the case for more urban Zürich inhabitants, who probably are just totally annoyed by this stereotype. :-)