The A320 engines take about 4 seconds to spool up. If you remember the Basle-Mulhouse accident many years ago I counted 3 and a half seconds on the video before the A320 hit the trees.
Unlike a Boeing 737 the Airbus is flown manually with the autothrust engaged. You don't get porpoising, as you do with the 737, because the 'normal law' of the flight controls keeps you pointing down the approach at 1G. Therefore if you get windshear just before landing this can reduce the thrust and it can take a few seconds for it to come back. I have sat next to a guy who was convinced that the thrust was not coming back, pushed the thrust levers forward out of the CLB (climb) gate - and the thrust immediately shot up to the thrust lever angle thrust. He initiated a go around. We didn't touch down but went around for a normal landing. That was in an A330 which has a lot of thrust available, so we shot up - much to ATC's surprise.