Personally, I try to arrive at the airport no less than two hours before our flight at MCO. Security can be long, and this is cutting it a bit closer than I like most of the time. As such, I don't mind leaving WDW about three hours before the flight.
Usually, it will take about 30-45 minutes to get to the airport, but I like having the extra time to drop off the rental car and get checked in.
This is why I like to fly into/out of Tampa more times than MCO lately, as the same three hours (1.5 to drive and 1.5 to get checked in and to the gate) usually results in a much cheaper airfare and a less stressful time.
Sorry this isn't the news you'd like to hear, but you will need as much time getting through security at MCO as possible.