Why does time fly when you're having fun?
'Time', 'Thought', 'Boredom' are synonymous. The boredom is excess of thoughts. Excess of thoughts not only kills your life force energy but also makes you feel 'heaviness of passage of time'.
The reason why you feel this 'slow passage of time' mostly at times of distress and when you're waiting is: you have too many thoughts triggered by the sensation of pain. In sleep, in coma, in meditation, your organism is using least number of resources and the number of thoughts are also less; therefore the time flies.