Real time is around 1:04:35. I started counting at fading in on 1st level, and stopped counting on the last ending screen, like in Hedgeg's PB run.

In-game time for every level: Village: 3:29.08 Next Village: 4:11.49 High Lands: 5:07.44 Green Wood: 3:46.03 Dark Swamp: 4:34.66 River City: 4:47.86 Pirates Island: 4:06.93 Treasure Island: 3:10.71 Sphinx Desert: 4:16.60 Oasis Desert: 3:18.46 Canyon: 4:11.43 Mountain Alley: 4:54.33 Dark Caves: 2:58.11 Snow World: 3:52.86 Iceland: 2:19.92 The Moon: 1:53.82 "Boss": 0:08.56 Assuming that my calculations are correct, total in-game time is 1:01:08.28.