Driving involves walking to your car in the parking lot, waiting for one stop light to take a left, taking a right on red at the second stop light, getting through security at the Poly gate, parking, walking to the lobby, and getting to the stairs or elevator (which are in the back of the lobby) in order to reach the Kona Café on the second floor. Parking at the Poly can be a pain. In addition, you could have half-a-dozen cars ahead of you at the security gate to enter the parking lot, each of whom will be checked by security.
The Monorail involves taking the escalator to the platform, waiting a couple of minutes for the next one, possibly longer if you are leaving when everyone's heading to the theme parks, making one stop at TTC, and then exiting the Monorail at the Poly. The Kona Café is immediately to the left as you walk in from the Monorail. It's not that unusual for Monorail to stop operating for a few minutes for any one of several reasons.
DW and I were shopping at the Grand Floridian last week and walked over to have lunch at the Kona Café. Meanwhile, our children were joining us from BLT. The Monorail was halted for a good 15 minutes. Consequently, they were about 15 minutes late for lunch.
IMO, either way, there are too many things that can vary to say definitively that one will be faster than the other. Driving (including all the extra walking) will probably take longer most of the time but there will be times when the Monorail will be longer.
