Time thru customs in Zurich for flight to Naples

Are you asking about immigration/passport control or customs? Customs, 99% of the time, is a nod and walk through the Green Door -- Nothing to Declare. ten seconds

Switzerland and Italy are in Schengen, so no immigration control. But in Naples, after you pick your luggage you will have to choose either the red or green customs channel. You should be through in seconds if you have nothing to declare.

Thanks to you both. So how long will it take to check passports for immigration?

I assume they check them in security check, right?

So how long will it take to check passports for immigration?

As WengenK just said, there is no immigration check.

Just arrive at the airport the standard 2 hours before your flight's departure and you will be fine.