Switch latency refers to the moment the switch is press to when the functions are actually executed. The MC controllers can be set up to have 0 latency, but by default, there is a minimal amount of latency added to help with dual switch presses (like Bank Up and Down). If there is no added latency, it will be very hard (if not possible) to execute dual switch presses.
How to remove the latency
There are 2 ways to adjust this latency.
The Switch Sensitivity setting in the controller settings can be set to 5, which is the highest setting. This will remove any latency when the controller boots up. However, you will notice that as the sensitivity gets higher, it will also be harder to execute dual switch presses. This is not a problem if you are using other means to change banks, like an external aux switch, or programming a preset to execute the bank change.
The switch sensitivity can be set in the Editor, under Controller Settings → General Configurations
The controller can also be put into a state called Looper Mode, which is similar to having the Switch Sensitivity set to 5. This feature is documented here: Looper Mode for Zero-latency Looper Control
Other factors causing latency
Double Tap action
If you have a double tap action programmed into your preset, this will add some latency, whether or not your Switch Sensitivity setting is set to 5 or whether you are in Looper Mode. This is because, when there is a double tap action added to your preset, the controller now needs to determine whether a press action is actually a double tap instead. Hence, for press action, there is that added latency where the controller is waiting to see if a second tap is going to occur.