i think its due to the fact that when we arent high everything is old, boring and has been seen. but when you are high none of that matters, you dont care that you have been seeing the same painting you look at for the past 15 years, you only care that the colors are amazing, and the lines so vivid. I think it is this "fresh" outlook that makes time seem slower because we are so amazed with the present (same thing said above just wording it they way i thought it to be). Ill compare it to being little... you remember when you were 5, and full of happiness, no matter where/what you were doing? remember how they days seemed soooooooooooooooooooo long? its the same thing. When your high you take in every little single moment as you do when your little.