Long drop (5-10 foot fall depending on weight + height) is instantaneous loss of awareness because it breaks your spinal cord. Short drop (under 5 foot fall) can be as quick as 10 seconds of conscious choking and panic. However in the worse case scenario the arteries are not cut off sufficiently and it could be 5-10 minutes of consciousness before you pass out. During that time you'd feel alot of pain like the rope digging in to your neck, windpipe crushing, pressure in your head + eyes, choking etc. I guess if you're successful the pain would be temporary but those last few seconds/minutes would be excruciating.