MUX re-configuration speed
The "switch frequency response" refers to the frequency of the signal passing through the switch. It is not related to how quickly the switch can be reconfigured. For example there are rf switches that can carry 20 GHz signals but require milliseconds to change configuration.

You are correct to look at the digital IO characteristics, particularly the timing characteristics on page 3 of the datasheet, to determine how quickly the switch can be reconfigured.