I didn't realize that Swiss trains apparently also adhere to the "schedule for 80% of capacity rule".
Apparently trains in Switzerland go around 80% of the top speed possible on the track. The 20% overhead is used to make up time in the case of delays.
The thinking is: stable and predictable operation is more important than going faster. Because the cost of passengers regularly missing layovers is much higher than the benefits of trains being 20% faster.