Any gringos with little patience for slow service should probably stay away from Cancun. The fact that the city owes it's sheer prominence almost entirely to foreign tourism, combined with the Yucatan Peninsula's staggering humidity, keeps Cancun perhaps a virtual opposite of such places as New York or Osaka, when it comes to a businesslike atmosphere. Customs is slow, ordering food is slow, and taxis are often rather late.
Plus--a tradition in the Spanish-speaking world is to take an hour or two off in the early afternoon. The siesta, it's called. You will stick out like a sore gringo thumb walking around and insisting on getting several things "done" during the siesta.
"Mexican Time" - Things just don't move as fast as they do in the US - but, if you are on vacation, why should you care! We find the Mexican people to be so much more relaxed, no one is in a great hurry. Meals are a time to celebrate being together, not just to fuel up! Sometimes you'll have to wait in line, or your room isn't ready the minute you arrive at the hotel, or the shuttle back to the airport is late. Hey, it's Mexican Time! Just relax and try to be patient. Soon enough you'll have to go home and back to the grind!