I just flew out of CUN. Lines are long to check in at ticket counters for document verification. If possible, check in online/app or use a kiosk. The document verification can be done at the gate if you have no checked bags.

Security checkpoint lines outbound are generally efficient. They want to get you through quickly to have more time to shop. Similar to LHR and MAD, they do not post the departure gate assignments until 60 minutes before departure, in order to keep everyone exposed to the "retail environment" as long as possible to maximize revenue.

Two other recommendations:

1) Have your Vuela Seguro QR code ready if they are scanning them at the checkpoint. Sometimes they do, and other times they don't. You need to complete the form online within 12 hours of flight departure time. Do it BEFORE arriving at the airport, and then screenshot the QR code, since the airport WiFi is not the best, and you might not have cellular data reception.

2) Don't lose your stamped immigration (FMM) departure card! By law, you must surrender it to the gate agent at the moment of boarding. Replacing a lost card is a huge hassle and expense.