Even though there is a worldwide agreement for providing security for public airline travel at all international airports, how security is enforced varies from airport to airport.  I have found that some airports may choose to impose even stricter policies which may required additional time.  And some airports are understaffed or still have an inefficient system for passengers to go through security screening.

Get your vacation off to a good start and allow ample time for check in and to go through security.  Three hours is realistic, especially if you are in an unfamiliar airport.