Time is just our perception of a physical phenomenon, physics as we know it is just an imprecise model, none of it is real.
We know that average speed is just distance traveled divided by perceived time to travel the distance.
I sometimes ride with guys who tell me their average speed is well over 20 mph, they invite me to ride with them and I cringe knowing my average speed is more like 18 over the course agreed upon. Usually what happens is I have no difficulty so their measurement of time must be different than mine - they must be experiencing relativistic time dilation effects which are not well model by our current understanding of physics. I suspect you are experiencing these same issues although in your case I am sure it does not skew your measurement of elapsed time - only your perception of elapsed time.
I hope that clears it up - there will be quiz at the end of class
