Tangentially, I'm relatively confident that what you're experience has provided you is simply confirmation bias. Unless French is not their first language.
Maybe I am racist, but I am not sure how the speed at which one speaks is a racist trope. I sure do not look down on the Swiss, they're a pretty successful nation.
Question for you: what is your relative confidence based on?
On the positive, your comment invited me to check Wikipedia and I was surprised to see there are actually studies about some of this. They seem to confirm the stereotype. Belgian and Parisian seem to have a higher syllable/ms rate than several Swiss counties, with some caveats. [1]
But no, it does not talk about total information bitrate, that is much more subjective. Maybe if you are a "frontalier" and have some anecdotal experience with it, I'm curious.
[1] https://fr.m.wikipedia.org/wiki/Fran%C3%A7ais_de_Suisse
"Après examen des différentes études, le stéréotype des Suisses qui articulent plus lentement que les Parisiens est confirmé, à quelques exceptions près"